Windows XP not showing full system memory

Hi,

I just bought a Inno 7950 GX2 1gb GFX Card.

I have 2 GB Corsair TwinX ram installed in the computer. When I goto System
properties in Windows XP and Vista RC2 I am only showing to have 1 GB.

So where has my other Gig gone

In Bios it is showing as 2 GB and was fine before I had the Inno card. Also
in Nvidia Control Panel System Information it is showing the two sticks of
Corsair Memory.

Anyone have any suggestions as to whats happening.

Thanks

Kevin

My Specs are :-

Windows Media Center 2005
AMD 64 3700+ (939)
Biostar N4-SLI M/Board (Up to date bios)
2gb Corsair TwinX DDR-400 Ram
Enermax 500w Power Supply
300gb Maxtor SATA Drive + 160gb Maxtor SATA Drive
Inno NVIDIA 7950 GX2 1GB GFX Card