Graphics upgrade for A8N32-SLi Deluxe

Hi, I am looking at upgrading my graphics card from an eVGA 6600LE to a 8600GT or a 2600XT.
Which one would be best suited for the motherboard? Would the 8600 go better with the NVIDIA chipset?
I have a budget of approx. £75. I have been looking at these:

256MB MSI 8600GT, PCI-E (x16), Mem 1400 MHz, GDDR3, GPU 540 MHz, 2x Dual Link DVI-I/HDTV Silent
http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=577065

256MB Sapphire HD2600XT PCI-E(x16) 128Bit 2200MHz GDDR4 GPU 800MHz CrossFire 2xDVI-I/HDTV
http://www.scan.co.uk/Products/ProductInfo.asp?WebProductID=633077

Spec is A8N32-SLi Deluxe with an AMD3200+ and 512MB of memory (looking for 2GB at the moment), running XP.
I am going to be playing Quake Wars and watching DVD's.
Thanks in advance.