For future reference you may want to try this website:
http://www.systemrequirementslab.com/referrer/srtest
You select the game before you buy it, and it scans your system to see if the game your...

Your lack of performance were cause by the 1Gb sticks running at a lower speed because of your of other RAM. There is a way of 'overclocking' RAM sticks, but it is quite complicated to do!

If we...

You can find out the clock speed of the RAM by looking at the sticker on the RAM itself. Or by using Crucial Tech's website to scan your system to show you what you have.

Are the 2 1Gb sticks new, and the 2 512Mb ones from before the upgrade? You may not notice a speed boost because the 2 1Gb RAM sticks are having to run at the old 512Mb clock speed. Can you tell us...

What amount of RAM did you upgrade from?
If it was 2Gb and you have placed in another 1Gb, XP doesn't show it because it can't!
It's a funny issue that i am not to clear on myself.
Are you...

Or it is a very rare limited edition one that has one thing slightly different with it.