Are you able to put it together yourself? you could make a gensui machine for about 400-500 quid with top notch gear if you buy the parts separately and make put it together yourself. this is what i did, and i also bought an Alienware PC case to make it look uber gensui. if you do want to buy parts separately i suggest you look at shops (online is cheaper) like yoyotech. they have great prices on their stuff. you wanna go for intel core 2 duo these days. although i used to support AMD quite a bit for their price and reliability, Intel have just gone the next step further and are unbeatable at the mo. graphics wise you want to go with ATI. Nvidia are power consuming cards (talking about the latest models within the last year) and ATI are just wicked. you might wanna wait a bit for the X1950XT to come out. it might be out now pozzibly, so check it out. As far as HDs are concerned, make sure you get S-ATA. they just work better, more convienient and easier to add more if you get a good number of slots made in ure case.
i got a mybook. good price, looks good and works well. though initially i thought it was better to get another internal, i still believe thats what i should have done. with progs like iTunes, having an external with music on it and trying to manage and keep your music playlisted on itunes is just a pain in the ass.