James, you don't trust me on this at all. You've been out of the market for about 2-3 years!
Paying a lot of money for a good motherboard isn't a waste! Also, the extra £20 would be better, which is why it's £20 more!
Also, I agree on the PSU. I have 600w and I'd like a little more headroom.
I bought a PC for £500 two years back.
I had a P5N-E SLI, E6600, 2GB RAM and a 7300GT. I thought it was going to be the mutts nuts. But it was complete crap. So I grabbed another 7300GT for SLI (stupid waste of money, imho) Also, my P5N-E motherboard was aweful. It was £79, cheap and didn't do what I wanted it to. The competition was about £50 more and having looked at reviews and benchmarks, AFTER I bought my P5N-E, I realised I'd made a mistake, I should've saved that bit more and gotten a better board, so instead 6 months later, I dropped £500 on just a CPU and motherboard combo and well over a year later I'm still running the same ones (though it is time for an upgrade

)
I told Goose not to get the Fatality abit 650i motherboard for the same price. I URRRRGED him not to make my mistake, but he got it anyway, then abit went out of business about 4 months later. He has to run his Q6600 G0(known for overclocking) at stock settings because his board is crap!
All I'm trying to say is don't scrimp because it'll bite you in the ass later! Get a good motherboard to go with that CPU, there's no point getting a £200+ CPU and a £79 motherboard that won't let you use it like everyone else does. I'd take that Q9550 and try squeeze 4ghz out of it, and you aint doing that on a £79 P5Q vanilla. The extra cash will be spent on all kinds of things like voltage regulation, better quality capacitors, resistors and transistors all in all amount to a higher FSB and thus a higher overclock.