Overclocking potential of a GF5600...what's reasonable?

[Idontcare]

I recently acquired an ASUS V9560...a dual-DVI output card equipped an FX 5600 with default core and memory speeds of 325/600 MHz respectively.

Bear in mind I already own the card (OT: do faster dual-DVI cards exist?).

Here's my question, what should I realistically expect the overclocking potential of this card to be? Should I be satisfied with 350/650? What is a typical overclock for this GPU and memory?

Thanks everyone!

Edit: poor grammar