However, here are a few recommendations. They range in price from FREE to several thousand US dollars.

These are my personal opinions and suggestions only, and there is lots of stuff I haven’t looked at, but we all have to start somewhere.
All the programs listed below are general purpose - other more specific programs are available. For example, there are now available architectural programs like ArchiCAD (Mac or PC )- or Chief Architect with which you draw objects like walls, roofs etc. which the program "knows" are walls and roofs, rather than just lines, arcs etc.
Or check out Sketchup - a FREE completely 3D based architectural concept program that is amazing in its simplicity and scope.
Some programs like Autocad or Intellicad have available different add-on programs which use the main cad program as an "engine" to drive their specific functions.

To see some of these 3d full architectural programs in action in competition, visit www.architecturalcadd.com/shootout.html

Another example of discipline specific CAD programs are those for theatrical lighting design, either as stand alone programs, or as add in modules. For example, there are add in modules for AutoCAD, or Vectorworks (see below) or WYSIWYG - a full 3D lighting design specific CAD solution.

Anyway, for what its worth:

Free CAD Programs:

Cadvance 6.5 - www.cadvance.com/65form.htm

[PC only] Originally sold in 1995 for U$1950.00 it is now offered completely free.

Flexicad LT - www.graebert.com/FelixCADlt_promo.html

[PC only] Entry level CAD completely free to the 1st 1 million users!

Justcad - www.justcad.com/

[PC only] 2D cad - "designed to make cad drawing as simple as possible" Import / export dxf.

ProgeCAD LT - www.progecad.com/

[PC only] Autocad LT clone powered by the IntelliCAD 5 engine. Reads 3D dwg info plus can create simple 3D files (like AutoCAD LT) Includes Wintopo raster to vector converter, plus PDF printing. Reads and writes any release DWG file from 2004 right back to v2.5. plus dwf format. Very comprehensive CAD and you can't beat the price! Tutorial on viewing and printing files on this site with ProgeCAD LT

A9Cad - www.a9tech.com/products/a9cad/

[PC only] 2D Cad freeware with dxf / DWG import / export up to release 2000. The company's mission is "to develop quick-to-learn, easy-to-use, affordable yet powerful software products for engineering students and professionals."

Design workshop Lite - www.artifice.com/free/dw_lite.html

[Mac or PC] An architectural based 3D program, originating on the Mac. Download the software, and then download heaps of famous buildings in Design Workshop format to view. Awkward viewing of imported 2d files such as those on this site.

CAD programs for the Mac:

I may as well confess right now I wouldn’t even know how to turn a Mac on - however, these people obviously do:

Pure Mac Cad - www.pure-mac.com/cad.html

Vectorworks - www.nemetschek.net

Mac or Windows. 2 & 3D. Many architects seem to like it. Has spreadsheet / database software built in, plus modules for various disciplines available - for example Theatrical lighting design.

DenebaCAD 2 - www.deneba.com/products/denebacad2/

Mac or Windows. 2D / 3D CAD. Download 30 day full evaluation. U$500.00

CAD programs for the Amiga:

X-CAD Professional

A great 2D CAD program available for this platform around 1990. Because it took advantage of the Amiga's inbuilt graphic processor, its zooms and redraws were very fast. It had features still not available on many programs today, and still a viable CAD solution if you have a fast Amiga and can find a copy of the software.
A classic example of how a superior product is not all you need to successfully compete.

CAD programs for the PC:

Generic Cadd6.

A fantastic DOS based 2D CAD program. Although development stopped years ago, (Autodesk bought the product, then discontinued it) it is a truly great milestone in CAD software with a life far beyond its development cut-off date. It can still be made to run on any windows platform including XP. See www.genericcadd.com/ for further info, especially the web support forum linked off that site.

"...We have tried every Cad program imaginable (Autocad 10, 12 & 14, Autocad LT 1, 2, Win95 & Autocad LT97, various versions of Microstation, DataCad, Design Cad, Visual Cad, Turbocad, MiniCad,............) to try to find something better than Generic Cadd for 2D production drafting - guess what? We're still pounding it out 10 hours a day with Generic Cadd - just can't beat it - got to keep it going." From Compuserve Aretail forum (Generic Cadd section)

Visual Cadd - www.tritools.com/

Version 5 available from TriTools - developed by some of the original Generic Cadd developers, reads and writes Generic Cadd files, and understands the Generic Cadd two letter key commands. Lost some of the original program's ease of use in the translation to windows, but has some very good features - fast, simple interface, excellent and easy to understand printing layout. U$ 395.00 or upgrade from any version of Generic Cadd, Visual Cadd or Autocad LT for U$195.95. Download a 30 day full demo.

General Cadd - www.generalcadd.com/

Essentially Generic Cadd for windows. Retains all the features of Generic Cadd, reads generic cadd files, plus additional features and improvements. Good online support. Requires a dongle to run. U$500.00 Download a save disabled demo.

Turbocad - www.turbocad.com

Checkout various versions of Turbocad here, plus download trial versions of some of them. Can also be picked up in most computer chain stores, and offers exceptional bang for the buck, plus they are usually stable and well documented. The interface is a little cluttered and fussy.

FastCAD - http://fastcad.com

Evolution Computing make FastCAD and EasyCAD. Both available as a 14 day trial download from their site. They are also the makers of the CAD viewer recommended on these pages. They seem pretty onto it, and update their products often.

Vectorworks - www.nemetschek.net

Mac or Windows. 2 & 3D. Many architects seem to like it. Has spreadsheet / database software built in, plus modules for various disciplines available - for example Theatrical lighting design.

DenebaCAD 2 - www.deneba.com/products/denebacad2/

Mac or Windows. 2D / 3D CAD. Download 30 day full evaluation. U$500.00

AutoCAD - www.autodesk.com

Large user base and the default standard on the PC platform, although many people consider it a very average and overpriced program. Autodesk update the product every year or so. Around U$ 3,750.00 - if you are a student you can get student pricing - about U$ 300.00.

Alternatively, you can buy Autocad LT (about U$ 600.00) - essentially the same product but with limited features - basically very limited 3D (although it can display any 3D entities created in Autocad), no programming language, limited selection tools, etc.

Intellicad - www.cadopia.com/ OR www.autodsys.com/

PC only. Autocad clone - older versions were free or discounted at places like warehouse for $19.99 - now buy online for about U$ 200.00.

Rhino - www.rhino3d.com

A 3D “NURBS” modelling & CAD program. Absolutely amazing software, with an equally amazing company behind it - excellent technical support, in constant development, with free updates for a year or so as the next version is publicly Beta tested.

Fully supported trial version available from their site, (save & print disabled after 25 uses) - the actual program is about $US 750.00. Excellent 3D tools, and 3D interface. Imports and exports a large range of formats. If you want to create and model in 3D, this is THE program.

Download it anyway to view (and print) the drawings on this site, and muck about with it. Download tutorials from the site also.

Tutorial on viewing & printing the drawings on this site in Rhino.