So, I'm a complete computer n00b and will probably be sent home crying for this post, but if you're not really interested in building a computer (or haven't the know-how), but want something a bit better than the prebuilt you're going to find at PC World, then I recommend
PCSpecialist.
They're quite simiar to that RCS website you linked, but I think they look a bit more professional.
They have a lot of great reviews, though.
They were really good when I used them for my Laptop this summer, and I was able to go for a cheaper item and upgrade on the areas I wanted.
And they had near-on next-day delivery once it was dispatched.
And one of the accessories I recieved (a fancy cooling-pad) was broken on delivery, and they had a courier come round the next day and replace it with a working one for free (as you would hope).
Furthermore, they have their own forum where you can discuss your build and share them, getting advice on them.
You can set up a build on their website without purchasing, but save it for a future date, and still get advice in their forum.
People here will probably scoff at the prices, or say it's just soo much easier and cheaper to build it (which I won't deny it probably is), but if you're wanting to go beyond your basic 2-year lifespan Dell pre-built, but don't want to go hunting for parts and nervously fumbling it all together, then I would suggest them as a pretty good middle-ground.
