NAS needed but with certain requirements

[Desmo]

Hey peeps,

I'm looking at getting some kind of NAS for work but I'd also like it to include some kind of backup feature with a removable drive.

At the moment I have an external USB caddy connected to my Mac for my jobs. I also have a second USB caddy as a backup drive that backs up the first using Time Machine for incremental backups.

A second machine (WinXP) connects to my shared jobs drive via the network to also work on jobs. This obviously means my machine has to be on for that machine to connect. Not a huge problem in itself but it would be handy if we had a standalone NAS unit.

The backup drive will be taken home with me each day to keep it off site meaning it needs to be easily removable.

To sum it up...I need a two drive bay NAS that will happily work with OSX and Windows and also allow incremental backups (still happy to allow Time Machine to do this) along with the backup drive being removable.

Does anything fit the bill?