Recommend an Upgrade for < £200

[MadLeo]

I have a budget of around £200 to upgrade my gaming system. Any spare parts "liberated" by the upgrade may also be sold second-hand to finance the upgrade. The basic remit is to speed up games and improve graphics quality (isn't it always?) as well as keeping it quiet.

Current Specs:

Antec Sonata Case (First edition I think with 350W Power Supply)
DFI LanParty UT NF4 Ultra-D (Not SLi modded atm but capable of it)
AMD Athlon 64 3000+ Winchester 90nm (S939) - mildly overclocked
GeIL 1GB (2x512MB) PC3200 Dual value Kit (CAS2)
Zalman CNPS7000B-ALCu Cooler
Gigabyte Geforce 6600GT 128MB - GVNX66T128VP - [SILENT NO FAN]

Any suggestions?

BTW I see "MM" mentioned where ppl buy/sell second-hand components what/where does this refer to?

 

[MadLeo]

Thanks for the advice ppl. Looks like a new graphics card then - any of the current OCUK deals worth going for?