Vista - games running slower than on old system

I just built a new rig

x64 Premium Vista
4gb of ram DDR3 (will be 8gb on monday)
9800GT 512mb RAM DDR3
Pentium Core 2 Quad 6600 2.40 Processor
M-Audio Firewire 410 Sound card


my old system was that but x32 bit system with 4 gigs of crappier RAM a 9600 GT and the cooling wasn't as good.

but for some reason my games run terribly slower on this system then they did on my dell....I don't understand it this is a better system already than my old dell ever was, i wan't to say it has somthing to to with it being x64 but that souldn't matter?

when i go into Mount & Blade it gives me a warning i only have 346mb of virtual ram (it fluctuates between that and 573mb) and mount and blade needs atleast 700 to run properly, could this have somthing to do with it?

Are you sure Vista is seeing all your RAM? Have you gotten into the BIOS to also check that you are running the amount of Ram you think you are?

yes it says in system and in BIOS that theres 4 gigs running, as of 5 minutes ago not it says im running 8 gigs, it doesn't give me that message anymore on mount and blade but im going to test other games and see if they run better now.