Here's what I have: one desktop that I use regularly with windows vista on it and 3 hard drives full of my game mods and photoshop work. I also have a small sony desktop running ubuntu server that I use to test web design/development work.

What I'd like to do is, set up my linux machine to host backup of the critical files on my vista machine: kind of like making the sony my version of apple's "time capsule."

Trouble is, I don't know where to begin. I have a Samba share setup so I can easily transfer files when developing, but I'd like to develop a more automated solution. I don't know if I would have this software on my windows machine, or on my linux machine. I'm not even sure where to look.

Does a solution for this exist?

well you can share out your hard disk on your vista box

then set up a cron job to mount your Vista hard disk and then execute a file copy from the mount to somewhere on your Ubuntu box.

something like this

mkdir /mnt/SOMEFOLDER

then in a cron file

mount -t cifs //SERVER/SHARE -o username=XXXX,password=XXXXX /mnt/SOMEFOLDER
cp /mnt/SOMEFOLDER/*mp3 /home/user/music
cp /mnt/SOMEFOLDER/*jpg /home/user/picutres

you get the idea...

I thought about cron, but is there a way I could make the job first compare to see which files have changed? We're talking plenty of gigs of data...I don't want to overwrite that every day at 2am...lol.

On the Windows machine you could use fsync in a batch file. Either call it manually or schedule it for automatic backups.