OK......I need some advise from users that Run Vista 32bit with 2X2GB Ram Kits please

I am New to owning Vista and I am also new to owning 2x2gb Kit of Ram and my question is this.....When using Vista what works well with Stability testing programs? Also what do I set in Prime95 for amount of Ram in MB to be used for Blend Custom?\\ I set 4000mb But Task Manager shows 2.16GB being utilized Is it just Vista or is it just me not being familiar with Vista or both?

So I need counsel on the Proper way to set up Prime95 Blend/Custom and HCI MemTest Windows using Phenom with 2x2gb sticks of Ram please