I think the SolidWorks viewer just allows you to view SW files. I don't think they have a trial of the modelling software, but Rhino does. Check this site out: Rhino 3D
It is a 3D modelling program that does 2D as well. The learning curve is pretty steep if you've never done any solid modelling before, but for 2D it seems to me like AutoCAD pre version 13. It's only $900, but if you are a student, you can get it for $200. I think you'd have to arrange something with your instructor to get it though.
Incidentally, I may (or may not) have acquired a full working version of SolidWorks 2003 on P2P - that site that begins with a 'K' And yes, it does work. I don't know if it is still "available" from the site what with all the lawsuits and stuff, but it's worth a shot. Be warned though, the learning curve for SW is almost vertical IMO
P.S.Actually, I think 2D in Rhino even resembles later versions of AutoCAD. It's got pull down menus as well as symbolic tool bars. Just to clarify.