i hc a 512 mb RAM and i hv set a page file of 758 mb and all of it is located in a partition other than the boot partition ...my computer uses more than 270mb mem even when no application is running..when i strt a multiplayer like counterstrike it zooms up to more than 470mb.. is this normal or can i improve my memory performance...

I would recommend setting page file to System Manage Size. Although your settings appear pretty average.

In XP you can also choose Set for best Performance rather than best Appearance.
Under System Properties > Advanced > Performance