I'd also add Scan.co.uk to your list as they have consistently good prices, the downside is that their lowest shipping is a flat rate of £6.99 regardless of when you want it.
As for parts, DVD+rRW drive has had some negative feedback, try the LG 22x speed drive or alternatively the SONY/OPTIARC 24x.
You could also try the Coolermaster Elite 330 low end range if you need to save a bit of cash without losing too much.
The Akasa fans are surprisingly powerful for the price but if you want more airflow try Scythe, Antec are good all rounders though.
I've never heard of Titan cpu fans but they may well be fine, I don't really follow cpu fans except when buying a new build myself. They don't fair too bad on this list:
Thx for the alternative on the optical drive spanner_razor. The Sony one is indeed better.
I have never actually bought anything yet from overclockers.co.uk, but they seem to be pretty good from what I hear.
As far as the shipping rates go it varies. I think small items u can get shipped for just over £3. If I ordered everything that I need for my system build the cost would be £12.50 (next day parcel I think). This ofc increases if you want it before 12/10/saturday or just ordering extra items. (You can also get free shipping with overclockers.co.uk if u happen to be busy on thier forums).
I quite wanted to go with Optiarc (as all my previous DVD writers have been NEC) when I bought my new drive (old one decided it would cease to read cds), but at the time they only had a 20x drive out so I went with the LG GH22NS40.
Apparently writing at over manufacturer's speed (typically 16x) can cause the drive to break. If you need some DVDs though Play.com has some Maxell's DVD-r for £6.50 (they're on my drive's reccomended media list for 20x burning, only some Mitsubishi discs can burn at 22x). As I remember - is better for data backup and + for video playback.
If you can find them in stock, dual Radeon 4770's in crossfire would give more performance for roughly the same price. You're only going to see negligible performance gains going DDR3, you could also go for an AM2/DDR2 system and use the price difference to upgrade the RAM density or opt for a beefier graphics setup, since you're into video editing, a second, but smaller hard drive just for the OS would be nice.
These comments are valid Infyrno but will they last three years, I'd be tempted to get a dual pci-2.0 16x speed board but then again maybe PCI-E 3.0 will come sooner than 3 years. Anyway why not get the Gigabyte GA-MA790XT-UD4P 790X, 2 quid cheaper on Ebuyer and has more features and no onboard graphics (extra onboard peripherals that you won't use will slow down performance.