Is there any potential risk involved in sharing? What should I be doing to protect my computer, my identity, and to limit access to the files that I wish to share. I'm running OS 10.2.6.

Your question is not easy: as another OSX user I have the same concerns. Connecting to the internet is a risk--I evaluate it by figuring out what I have to lose and trusting that I've nothing very compromising on my hard drive. Really, my stuff isn't that interesting.

Easiest and safest way is not to share anything popular, leave the firewall fully on, and don't download anything that looks like bait. This means living as a leech. Your identity (IP address) will be available if you connect to the internet. I don't know how (or if it's worth the hassle) to learn how to disguise your IP.

Still, I'd rather take the low risk of a virus or hacker than be a leech. The whole idea of Gnutella falls apart if no one risks sharing. I've read of some people who only share sets of files for a week and then share others by setting up a series of folders. In the six months I've been trying to fully share (I want my upload stats to be higher than downloads) I haven't been hurt yet.

This is far too general. I'm interested in a better answer.

Yeah, to give you a sense of the chances, I run OS 10.2.6. More or less 24/7 for the past say, month, i've been running Limewire. I keep five slots open, i'd say on average at least three are filled all the time. So, let's say, over the past month, perhaps thousands of files have been uploaded. I think that's a fair estimate. I've never had a problem.