64-Bit System

[ZiNgA BuRgA]

Do you mean, run a 64-bit OS?
If so, all you need is a x64 capable CPU - pretty much most CPUs made in the last 6 years support x64, starting with the AMD64 and Pentium 4 Prescott lines (with the exception of some Intel Atom CPUs, IDK about Bobcat).
In terms of recommended requirements, you'll probably want to consider if you have enough RAM, since 64-bit will consume more than 32-bit (so, for a low end VPS, 32-bit is probably better in most cases).