Currently I have a 600watt PSU. I haven't checked if there is another connector for a second VGA, but would this be enough power if there is? Or should I look into buying something with a bit more juice?

What is the brand name and model number for your PSU?

It is a Xion, and it says on the side: XON 600F14-TN, if that is what you are looking for?

Yes that's it. It should be fine, however if it does not have enough PCI-E connectors (see edit) I would look at something like this:
http://www.newegg.com/Product/Prod [...] 6817139002

or this: http://www.newegg.com/Product/Prod [...] 6817139006

or even this: http://www.newegg.com/Product/Prod [...] 6817703005

Don't buy them from Newegg though (unless they have the best price on them ); their prices on PSUs are usually higher than many other sites.

EDIT: I just looked at the PSU specs again and yours only has one PCI-E connector. In that case I'd say go ahead and get one of the aforementioned PSUs I listed (I like the Corsair 750TX for the sale price )

Man, setting up SLI is costing me nearly as much as just buying the newest card.

Would something like this do the trick?
http://www.infonec.com/site/main.p [...] &id=309935

Yes the TP3 650W is even 8800GT SLI certified. It's a good choice.

I run SLI 8800GT with an OC'ed Q6600 and 4 drives with the 550W version of that PSU.
This one: http://www.infonec.com/site/main.p [...] &id=187284

BTW, a new card like the HD4870 consumes about the same power as SLI 8800GT. SO, remember that when factoring in costs of the latest card too. A pair of 8800GT's will more often than not outperform it too.

Sweet, thanks!