Graphics drivers in Bootcamp (4:3 aspect ratio)

I am thinking about playing with updating the Windows graphics drivers for the ATI GPU in my new iMac (late 2009) in order to try and force old PC games to run in 4:3 aspect rather than being stretched.

Will (can) updating the Windows drivers in the bootcamp partition affect OS X at all?

Is there another solution to getting software to run in 4:3 under Bootcamp/Windows XP?

Thanks

Matt