Nearly. I use Parallels Desktop for Mac.
http://www.parallels.com/
Obviously this only works if you have an Intel based Mac. Older macs that use IBM/Motorola processors are not compatible.
Parallels works a treat though, i use it with an offical Ross-Tech HEX-USB+CAN lead.
I'm pretty sure you can probably use Apple's Boot Camp as MarkE suggests also. Boot Camp is a free beta at the moment from Apple. But is slated to be part of the next OSX revision 10.5, from then on the beta is expected to expire.
I prefer Parallels though, because i do not need to reboot the Mac into WinXP. I can just run WinXP from within OSX the same time.