TW,
I just got back from a customer's house on the main line who had this issue.
Mac OS X has CUPS. Grab 1.2rc1 from
www.cups.org, install on the Mac, and share out the printer from there.
Set up the shared printer as an Apple Color Laserwriter 12/600 on the XP box.
You will then have happy printer sharing.
And in case y'all are wondering, I did this on an Intel-based iMac Core Duo, so I know it will work with both Intel and PPC-based macs.
Mitch