Ok, I am looking for software that will only backup the changes that were made on the disk. Basically, if anybody has Time Machine from Apple, I'm looking for something like that for XP. I have all my docs and music on a partition and want to e-sata it to my ext. 400gb hdd.

Thanks.

I'm using Goodsync and works really well. There's a free version you can try. It's $20 and I think it's money well spent is you do frequent backups.
http://www.goodsync.com/