Most hardware out there has both platform drivers available, if they offer Vista drivers. Hardware probably isn't going to be the issue. The vast majority of applications work fine under either platform of Vista. Considering 4 GB will be the norm during Vista's lifespan, unless you have a specific incompatibility, I'd go straight to x64. I had Vista Ultimate x86 and upgraded to x64 once I got my full 4 Gb of memory, and haven't looked back. If anything, it's a bit snappier than the x86 version was.