DDR3 is not worth it, performance gains are very small and not noticable to the every day desktop user.
I would get a higher end X38 motherboard if you're planning on using CrossFire.. simply because you will have two 16x PCIe lanes.. where as on the P5Q Pro, only one 16 and one 8x.
As for the CPU, lovely.. I wouldn't mind one myself
The PSU.. I would strongly recommend any good known brand over 600w, the TT is a brilliant performer though for £68 I think (off the top of my head) you can get a 730w Hiper, which is a brilliant PSU and I would recommend it to nearly any one
The case.. Antec Three Hundred is what the doctor ordered!