While you're waiting for a more informed reply I will can offer the following thoughts:
1. You might want to post this question to a different discussion group as this isn't really a Revit question and you might find nerdier (hardware) types in another area.
2. Your issue is clearly not related to your proecessor or RAM. I run revit on an i5 laptop with 4 gigs of ram and don't have a problem other than my graphic card crashes on occision.
3. 5400 rpm hard drive is a bit slow and will definitely have an impact, but how much is hard to say.
4. You don't mention your graphic card spec beyond the fact that it's a GEForce card. There are many, so you might want to be more specific.
5. You also don't mention your OS. If you're running an i7 processor you probably have Windows 7 home premium or better, but certainly if you're running an older OS that could also be an issue.
6. You might want to start by doing something as simple as cleaning up your hard drive to see is that improves your performance. You may have some sort of spy ware or virus running in the back ground. When I run revit and autocad simultanesously on my laptop I never use more than 3.5 to3.75 gigs of ram.
Good luck
SG
