8600gt xxx vs. 7600gt ddr2

I've never even heard of a 7600GT with DDR2, sure it isnt the 7600GS?.
Even so, if you want to upgrade in order to play DX10 games, dont get the 8600GT as it struggles more than a X1950pro in DX9, let alone 10.

What do you want to use it for?

Just games or for a HTPC or something random?

If you want a big upgrade then buy either a X1950Pro or X1950XT, not the nvidia/ati midrange crapfest.

SAPPHIRE 100176L Radeon X1950PRO 256MB 256-bit GDDR3 PCI Express x16 HDCP Video Card - Retail

http://www.newegg.com/Product/Prod [...] 6814102061

OR

SAP PHIRE 100186L Radeon X1950XT 256MB 256-bit GDDR3 PCI Express x16 VIVO HDCP Video Card - Retail

http://www.newegg.com/Product/Prod [...] 6814102067

And by the way, just so you get used to it, if you're making a gaming computer the part that you have to spend the most on is the graphics card, not the CPU or motherboard.

Agree with Emp. Make sure your PSU is a quality model that can handle the load. A GPU upgrade will need the PCIE connector that your 7600GT does not require.

Ok so i googled your mobo and it says its a sli board which is pcie not agp so what jtt283 is talking about is the 6pin pcie auxillary power connector.Your card can get all the power it needs direct from the pcie slot on the mobo but a card like a 1950xt will need to have the extra power from the extra power connecter.
This is why you need to check your psu before you start looking at these cards to see if you have the power to run them.
You can google the make and model if you know them or take the side of the casw off and look on the sticker on the power supply i would do the second as ther can be no mistakes this way.
You should be looking at the +12volt rail/rails you are looking for at least 25 amps.
Mactronix

The difference would be huge. Just make sure your PSU can handle it. It's recommended that you have a 450W PSU with 30amps on the +12V rail.

kaotao is correct on both points.

Go for the saphire card its clocked very slightly higher not enough to make a differance but the thing that swings me is the price and the fact that you get all the cables and connectors you will need included in the price.
Mactronix

Both are radeon cards, except one is branded ati and the other sapphire, no difference at all.

I guess you're right, I didn't finish loading the links after I read Ati Radeon and Sapphire Radeon. But bundles aside, Ati tends to greatly overprice their Ati branded cards that are really no different than sapphire ones. And oh please god... don't let a goofball come here and talk about different clocks on each, because the card itself is the same.