I also feel that the AMD Athlon II is the best choice for you. However no one has mentioned the Athlon II X4 Quad Core E variant CPU's which only use 45w also and might be preferred given the gaming requirement, unfortunately OCUK don't have any listed but the same is also true for the Dual Core ones...
Here are the details of the two quads:
AD600EHDGIBOX - AMD Athlon II X4 600e Energy Efficient Quad Core, S AM3, 2.2GHz, 2MB Cache, 45W, Retail
AD605EHDGIBOX - AMD Athlon II X4 605e Energy Efficient Quad Core, S AM3, 2.3GHz, 2MB Cache, 45W, Retail
They are definitely worth a mention. I did glance at them but I'm somewhat concerned at their single-thread app performance.
I can understand spending a lot of money on a good chassis although £200 is probably a bit OTT . . I assume its gold plated with a built in LCD touchscreen for that kinds money!
Does look good though!
Can probably get it for £170-ish but will likely cost more to get from a preferred supplier. My other cases consist of: Lian Li PC-A77, it's little brother Lian Li PC-A17, Coolermaster Cosmos (v1) and a mini pc (Philips LX3000). I see all my cases as pieces of furniture so I like them to look as good 5 years down the line as they do now.
Are you building a HTPC or are you building another gaming PC for your lounge, you really don't need to spend big money on anything apart from a nice chassis (which u got specced already) and a nice graphics card that runs cool but is powerful enough to drive a 1920x1080 gaming session . . . that's the only challenge you have really and that's where the bulk of your money will be spent if your wanting some serious fps
I don't like consoles much so I would like it to also be my gaming centre for the lounge. Obviously gaming on a large TV is a different experience to keyboard+mouse in front of a relatively much smaller monitor. I'm positive the Athlon II 240E will serve all my needs now, and in the future, except I don't know for gaming. When playing games at 1080p with say an ATI 5850, what will be the bottleneck, CPU or GPU?
Lastly I'm not convinced the *e* versions of the Athlon II are worth a Premium as the regular Athlon II's seem to undervolt pretty well (assuming you choose a motherboard with vCore adjustments).
£13 difference at one supplier (~£43 vs ~£56) - I'll just have to go lighter on the accelerator pedal for a couple of weeks

but seriously that kind of money not many people will lose sleep over - hardly what I'd call a premium.
It's exciting to spec and build an expensive machine but things are moving so fast now that as an investment it doesn't make sense to spend big bucks on hardware today that will be outmoded and outpriced by the new tech coming through in 2010, your money spend it as you wish but there really is no need as the budget kit for sale doesn't perform like budget kit anymore, it's high end!
That's always been the case and it's good advice but if you followed that advice ALL the time then you'd never have anything --nice--. Sometimes impulse buys can be good! I understand though when you give advice to people that's what you have to say everytime as you don't want to be responsible for people spending more than they need to - and yes budget kit these days is comparatively faster than budget kit of a few years back - hence why I've not ruled it out.
PC equipment depreciates VERY quickly. That's why businesses can write off PC equipment as having no value after just 3 years (50% depreciation in first year then 25% + 25% for years 2/3). That's unlikely to change anytime soon so the choice is simple. Buy what seems like good value kit then upgrade every few years or spend a bit more and buy what you like and it will last longer SO LONG AS you forget about how much quicker new kit is. Example: I bought a P4 3GHz chip on launch day along with the original Raptor HDD which had also just launched. That PC lasted me well for 5-6 years of heavy use and in fact is in my Cosmos case now still running - but history sees that chip as pretty poor because of the standards we're used to now. A couple years ago it was replaced by a PC based on the Q6600 GO @3.2GHz. It is still serving all my needs as well as it did on day 1 because my I'm still running the same applications. I can't see myself replacing it for quite a while yet.
Buy a cheap dual core now if its good for your current tasks. If you ever need more CPU power you can upgrade to Quad/Hex core. AM3 is supposed to last quite some time
One of the reasons I hate upgrading CPUs is because it either means you're throwing away a perfectly good CPU or you have to buy a new motherboard + ram as well and then you have to find a home for the old kit.
For gaming the Phenom II 550 is a great CPU. There is always the chance that it could unlock to a Quad too!
80W... a little high just for a dual-core - baring in mind the Q9550S comes in at 65W. I'm sure it's a great bang for buck CPU if low noise isn't the top priority (and price/value is).