The motherboard you suggested should do. The disadvantage is that it doesn't support DDR2-800, so you won't be able to upgrade to faster RAM later. Since you're not overclocking, this isn't a big deal; 667Mhz RAM provides enough bandwidth.
I still suggest prioritizing the video card over the 2GB of memory. You'll notice a much larger improvement spending the money on the video card. Moreover, you can easily get another GB of RAM anytime later, while upgrading a video card implies selling the old one.
Also, an E6400 is not worth the extra £20 in my opinion. Let's stick to an E6300.
Processor:
Core 2 Duo E6300 -
£123.29
Motherboard:
Asrock CONROE945G-DVI i945G -
£46.87
Memory:
Elixir 1GB DDR2-667 C5 -
£58.15
Video Card:
Sapphire Radeon X1950XT 256MB -
£176.12
Optical Drive:
LG 18x Dual Layer DVD+/-RW/RAM Black -
£20.67
PSU:
530W HiperPower Type-R Modular Black -
£49.35
Case:
Akasa Zen Black Silent Cool ATX -
£29.95
Total:
£504.40, VAT included.
Remarks: no hard drive, monitor, mouse, keyboard or speakers.
That X1950XT is a beast, as it seems to beat a 7950GT. It'll last you a couple years before becoming outdated. We had to sacrifice 1GB RAM, RAM speed and motherboard quality, but I think it'll be worth it. If you wanna save a bit more, downgrade it to a X1950Pro or something similar.
As for the PSU, I still prefer the HiperPower Type-R over the ones you proposed. It is rated at 530W, and has dual +12V rails rated at 20A and 17A (37A total). The Seasonic 430W is nice too, but its +12V rails are rated at 14A and 15A (29A total). The HiperPower simply delivers more power at only £3 more, and it is modular too, which is nice to have. More info on this PSU at the
manufacturer's website.
The DVD burner is your choice, really. Most burners cost around £20, so just choose whatever brand you prefer, it doesn't really make a difference.