OK, so I just went for it and have ordered an XFX 7600 GS 256mb.
...I hope that wasn't the moronic option. It was £72, ($137), and i'm sure in the USA I could have got it a lot cheaper, but I think gfx cards are a bit more pricey here in the UK.
Here's the link.http://westavon-systems.co.uk/pd_256mb_xfx_7600gs_agp.cfm
They wanted me to pay by bank transfer, as opposed to credit/debit card. Sounds a bit dodgy to me, should I pull out or is that perfectly normal?
Thanks everyone for the really helpful replies.