screw turbocad, when you click the link it doesnt download turbocad, it sends you to a link with a ton of other free cads, i have found the best to be deltacad, i was going through the same thing you were and it took me a year to find it, so save yourself the trouble and use it:
http://www.deltacad.com/demo.html
besides, most the people on here send you links to cad sites that cost money even when you keep telling them you want FREE program, i mean seriously, how dumb can people get, if you dont want to pay you dont want to pay, but deltacad has worked great for me so far, so i suggest using it