Just wanted to post that after some digging, I found a work-around for this. Just have to install the BootCamp Assistant from the command line instead http://forums.macrumors.com/showpost.php?p=6918301&postcount=1

After reading this, I wiped my 32-bit Windows 7 partition and reinstalled it as 64-bit, only to put in my OS X disc to install the Bootcamp Assistant, and be told that 64x is not supported on my computer model. Is there any way around this? The 64-bit Windows is working wonderfully. I have a late 2008 24" iMac, 4GB RAM, 3.06GHz processor, NVidia GeForce 8800 graphics card. I know I'm not going to get stellar frame rate no matter what I do, but I had hoped that at least having access to that last 1GB of RAM would give me some improvement. Even with totally up-to-date Nvidia drivers, AA/AF off, all the other settings switched to Performance (over Quality), I'm still getting between 8 and 20 fps consistently in game (when I was on the 32-bit OS). Still installing for 64-bit.