Since you posted in the Windows 7 section, I assume that you're running Win 7. If that's the case, 1GB RAM is way too little. Try to upgrade to 2GB at the very least, preferably 4GB. It's hard to say for sure that the problem is caused by insufficient RAM, but it could well be.
Some will say that even 4GB is not enough, but I manage quite well with 4GB myself since I don't play demanding games or do heavy CAD work. I do use CAD software regularly but it's mostly 2D electronics design work which is less demanding than 3D.