www.blackviper.com
Very helpful website in regards to tweaking. There are a lot of background services you want to disable to speed thing along.
The machine I am typing on:
AMD X2 4200 (2.2Ghz)
2Gigs Ram
ATI X1650 Pro card (yes its older but works fine)
Onboard sound and nic.
My "Windows Experience Index" is 4.4 - and my pc runs a slight bit faster than XP pro on the same box. However, if I add Ram the increase at this point is dramatic.
In your case - its not ram. There are three glaring possibilities. First - turn off all the background stuff thats not needed. Second is the possiblity that you need a mb driver for something like the north/south bridge pair. If that is the case, do not expect Windows update to do this for you. It won't. You should get the MB manufacturers driver from their website for your board. This often has a dramatic result. Lastly - it may be a bios/OS setting your missing. Make sure that windows is seeing all your Ram. It could be a timing issue that keeps it from utilizing all it should.