I think it is funny that people think that 64bit OS's are these awesome huge speed increasing demons.
The only benefit of a 64bit operating system is memory access and more memory registers. That's it. You are not going to get this huge speed increase...actually, you might even see decreased performance. Anyone who tells you differently is lying. When software is written exclusively for 64bit architecture you *might* see a slight performance increase. Ask any major software developer and they will agree. 32bit compilers are still not even close to being maximized for performance, let alone 64bit compilers. It will be several years before 64bit compilers will be optimized to take advantage of pure 64bit processing and even then only marginal performance boosts are expected.
Point is, 64bit will not be any faster than 32bit for, at minimum, the next few years....and certainly will not be any faster than what you are using now. Add to that support for 64bit drivers and hardware compatibility to take advantage of these benefits and you have one big mess.