I've been successfully using Mozy on my work notebook (Windows XP) since I found out about it. I also set up Mozy on my iMac at home, but it gave me some troubles after a few days. I couldn't get too worked up over it since the Mac client was in Beta.

Good news, there has been a refresh on the Mac beta, and at least for me, it's working great now.

If you're not familiar with it, Mozy is a free online backup service for a 2GB account, and for only $4.95 you have unlimited storage. It's a really slick setup that I use and recommend. Click this link or the image below to signup with my referral, this will give you an 2.3GB instead of just a 2GB account.