Mel,
If you are on a tight budget, then you have a decent machine. My secondary machine has an Intel 2.66 GHz quad core/8GB RAM/2x-nVidia 8800GT. It does well, but I recently re-installed Win7 and “cleaned house”. I am very careful what I do with my computers and I am not in the habit of clogging them up with useless software. I mean to say that I keep them pretty trim. If your computer is the one you would test trial software and freeware, surfing, email and such from the internet, then I would pick-up a used laptop to do all that with and clean out this one by doing a fresh install. You will find *ANY* version of Vegas will run better and be more reliable with a clean system.
Jeff
http://www.narrowroadmedia.com