Well at Play.com they have the ModXStream Pro 500W for £50 and the same 700W version for £52 so I really don't know whether to buy the 700W version. The only reason I might want to in case the 500W is not enough but the 700W might be overkill lol. I am going to be powering up a Q6600 at stock, 5770 overclocked, 4GB DDR2 RAM (4 sticks) and about 3 or 2 stock case fans (probs 80mm). From different PSU calculators I've been getting recommended power rating from 330W-450W. So should I buy the 500W or 700W?