Hello Bolox and FerchogtX, welcome to the Seven Forums.
Yes, as FerchogtX already told above, XP Mode is always 32-bit, even if you run it on a 64-bit system. You can not have a 64-bit virtual machine on Virtual PC, so even if you install XP, Vista or Seven from your own install media to a virtual machine, it has to be 32-bit.
XP Mode emulates hardware, it does not use for instance the graphics card of your host system. The GPU it emulates is an old
S3 Trio 32, which is not capable to run the most modern games. You can try; some older games run nicely on XP Mode.
You can not change the emulated GPU, so there's no way you install better
drivers.
Kari