Sorry, I missed that part. Read a few posts and the OP only.
In that case you fit under budget well, I'd suggest getting something of this proportion:
Radeon 5850s are back at £200 and are really good graphics. You can get one now and another on a later date.
Benq is a good monitor although if you are looking for a quality monitor, I would have a look at Dell U2311H reviews. It costs £80 more but may be worth it in a long run.
OCZ Gold memory has gained some bad reputation in these forums but mind you, most if not all complains come from Triple Channel owners. I've yet to see dual-channel memory that causes troubles. This one is cheap as chips and will be fine with overclocking the Phenom II as it's an unlocked multiplier edition anyway. You can always replace the memory with faster G.Skill kits if you want.
The board will do symmetrical Crossfire, won't do SLI though. Cards run relatively cool and quiet even after overclocking.
PSU will be enough for an overclocked rig.
You can always change the CPU cooling, it's just a suggestion.
LG optical drives have the least complains and RMAs.