Keeping two drives in sync with something like rsync?

[goodcow]

Time Machine is extremely limited in terms of its options, and can't do what I want it to do.

That is, backup "A" to "B" AND "C" to "D."

I am using Time Machine to backup my internal drive (A) to an external (B).

However, I have two 750GB externals where I keep all my data (C and D). I'd like to keep these two synced at all times, basically. That also means I don't want the usual one hour Time Machine delay.

Is there a program that's Leopard compatible with a GUI that can do this?

Any suggestions on how to do this would be great.

Thanks!