Parallels Desktop 7 + Boot Camp 4.0.3

I think I should post it here so, here it is.

I have Parallels Desktop 7 with windows XP installed in it.

As we all know, the windows XP in parallels desktop 7 has no nvidia/ati graphic card so it disables me to play games that require graphic cards.

My thought is, I will install windows 7 64-bit using boot camp. And there's no problem.
but I want to use windows 7 64-bit with boot camp ON Parallels Desktop 7.
is it possible? if yes, will the graphic card of my MAC OS X 10.7.3 be recognized so that I will be able to play games on Windows 7?

further question, What do I need to install windows 7 using boot camp aside from an ISO image of windows 7?
I only have a 4gb USB drive, will it be enough? the size of ISO images of windows 7 is 3.5gb but Im wondering if the Windows Support Software from Apple be able to be transferred to the USB stick because of lack of space..(?)

by the way, thanks for answering this question