32-bit vs 64-bit Cryostasis gameplay

[idiom]

I'm running windows XP pro 32 bit and these are my specs:

Intel Core I7 920 @ stock
6GB Ram @ 800MHz CAS 7 triple channel
ATI HD4900 1GB

I run the game @ 1920 x 1200 with maxed settings with AA and AF on, shader model 3, and Physx turned off. It runs fine, although after about 2 hours play I did turn down shadows a notch as it had gotten a little treacle like in some places... after that I got around 30FPS solidly though the game.

[boredgunner]

On Vista x64, the game ran great with a single GTX 260 CORE 216 and a 9800GT dedicated to PhysX. Now that I'm running two GTX 260 CORE 216s in SLI, the game ALWAYS crashes, unless I disable SLI. Hardware problem, or game problem? I have no trouble elsewhere with SLI.