Vista - PES 2008 problem

Hi all

I recently brought a new pc, i have got XP and vista installed on it, PES 2008 on vista and XP just will not run properly. Whenever i try to run PES on vista i get this error message saying my pc dont have the necessary specifications to run this software and something about my video card dont have the necessary (VRAM 64MB) my system spec is, AMD Athlon(tm) 64 x2 dual core processor 6000+ 3.00 GHz, 4.00GB RAM and on vista iv got ultimate 64-bit. my graphics card is NVIDIA GeForce 7900 GTX, to my limited knowledge i think that spec shuld run the game perfectly?

I tried PES on XP and i dont get the error message but when i start to play the game its so laggy its impossable even on lowest resolution.

I have tried to run the game as administrator and installed new drivers on my graphics card and thats about as far as my knowledge goes lol. any help would be much appreciated