When I ordered my 8K3A+ I got a 512Mb stick of OCZ PC2700 to replace my 256Mb of Crucial PC2100. The OCZ ram I got was one of the cheapest 512 sticks on Newegg and seems to overlock much better than my PC2100. Is there any reason for this, or is just that I got a better stick this time?

Also, I'm running WinXP and when I had 256MB of RAM the system used all but about 50Mb with very little swap file usage, but with my 512 stick it still uses all but about 50-75Mb. Does windows keep more stuff in the RAM according to how much you have?