I'm not sure I'd trust my PC to a £13 PSU
For a Q6600 with a decent graphics card just look for something >500w made by a manufacturer you've heard of, as a general rule Antec don't make bad stuff so anything by them will be good
The Q6600 is a power thirsty chip even at stock, I used to struggle to keep mine (@3Ghz) at sensible temperates without being too intusive noise-wise, yet the same cooler handles my i5 2500k @ 4.8Ghz no problems.
A good PSU is an investment as you can carry it over from machine to machine, they do loose their maximum output as the components age but that's why you buy a decent one in the first place, 500 Antec watts are more than 500 cheapo PSU watts...
I suggested the 260 as I had one which lasted me about 3 years playing the latest stuff, I only made the jump to a 580 so I could run BF3 with all the shiny on
A GTX460 1Gb is about the biggest bargain around right now, a little more oomph than the 260 and they are around the £100 mark brand new, less heat/power and DX11 capable too.