Thinking about buying an iMac and running XP on it? Well if you want reliable wireless networking, just don't bother. The BCM43xx driver version 4.170 will frequently lose its connection leaving you stranded for 10-20 seconds, or possibly until the next reboot.
Apple produce new bootcamp drivers slower than Dell release new Nvidia drivers, and unfortunately, because Broadcom don't release reference drivers, there's little hope of a fix anytime soon.
Oh, and speaking of Nvidia, I've been unable to find any reliable way of getting updated graphics drivers either. Laptopvideo2go doesn't have any yet.
Oh, and it took me 10 attempts just to get boot camp working. Supposedly a simple process, it seems to be very easy to end up with a black screen with a cursor flashing in the top left corner when it's supposed to be booting off your XP install disc. The forums are full of complains, but no answers and Apple provide absolutely no support for boot camp, so if you're one of the unfortunates who hits this problem and doesn't manage to get through it by partitioning and re-partitioning and re-partitioning again, then you're just screwed.
All in all, if you're thinking about getting an iMac to use as a Windows machine, you really are better off just putting up with a few more wires and using a proper Windows PC. I wish I'd never bought mine, and I'm considering writing off the $2,200 I paid for it and giving it to a school.