I too am an Acronis user. I also use Windows XP and I have Pogoplug set as a drive. It works exactly like it's described. When you get your Pogoplug (because I know you'll end up getting one :-) ), download the software to make it a network drive. Once you've done that, you'll see it in "My Computer". From there, you can just point Acronis to the destinations and BAM, you're done! Pretty easy.

The only thing I had an issue with when I first got my Pogo was making Acronis create a backup from the Pogo, to the Pogo. Does that make sense? Both the source and destination were attached to the Pogo and for some reason, Acronis didn't like that. However, with the newest firmware release, this issue might be resolved but I'm not 100% sure. Creating backups of things that were ACTUALLY on my PC worked fine though.

Good luck!