There is no partition size limit that I am aware of, but there is a file size limit. I *think* it is 2 Gb.
By the way, Peakoverload has good advice - use HFS+ and get MacDrive for your PC. HFS+ is a much better file system - it supports file ownership and permissions (important security considerations) AND it is journalled, making it far more resistant to corruption caused by things like sudden power failures, and faster to auto recover from any corruption that may occur due to other causes. Plus of course, it is the best supported file system on the Mac!