Which is best buy of the TWO.. desperate

Specify your mobo model, and your PSU model...
And your mobo just have to have a PCie X16 slot to support the graphics card...

And here are few better options...
Just about £8 more than the 9600GT but would perform as good as the 9800GTX+/ GTS 250...
ASUS ATI 4770
http://www.scan.co.uk/Products/512MB-Asus-HD-4770-PCI-E-20-(x16)-Mem-3200MHz-GDDR5-GPU-750MHz-640-Cores-2xDVI-HDTV-HDCP

But if you still want to buy a 9600, then get this one...It has 96 Stream processors compared to the 9600GT's 64 Stream processors...
http://www.scan.co.uk/Products/15GB-XFX-9600GSO-580MHZ

or the 9800GT for £70 with Free shipping
http://www.ebuyer.com/product/169143