Pab
I have watched this thread with interest, as I always like to see the very definite advice given by people who may have experience of one or two brands only. 'buy x as they are great' is a very definite statement, but may not be based on knowledge of the complete range available these days tbh.
It is going on a bit long now, so I thought I'd throw my 2p in now.......
1) Do you honestly think that the interior of a Dell differs much from say an HP, PB, Acer, etc? Not really, most of the big manufacturers/assemblers are buying from similar sources, and their parts are all of a similar quality (unless you go to some of the more expensive options of course).
2) For a basic desktop PC, it will hardly matter that much which one you go for, just buy one at the top end of your budget and ensure you look at getting the best specification you can for your money.
3) If you are looking for something a little more than usual, then explain your needs on here and we will advise on some spec details you should look at.
4) Do not take the advice of someone who has had 3 machines of the same brand and has never had problems with them, so they must be the best manufacturer out there
Ask for some of the guys who get Pc's in on a daily basis for repair which are the best ones..... and I can easily tell you that they are mostly of a similar quality. HP have made some shockers, Dell have made some shockers, Acer, or anyone else you'd care to mention are all capable of making a shocker. Likewise they have all had their decent machines too. I can tell by the machines that I get in though, the quality is not just the same in a lot of the newer ones.
You inevitably get what you pay for, so as the market demands cheaper and cheaper, then so too will the quality decline. don't even get me started on the laptop market, it is becoming as disposable as razors !
I know, because I build PC's. We supply custom-built PC's, built to a specification that I would personally buy. They do not always compete on price with the off-the-shelf machines, but I stand over every component as being one of the best manufactured available. I refuse to save a fiver on the price of a HDD, buying an inferior brand - this to me is a false economy. I also put a lot of faith in future upgradeability, and this is lacking in a lot of the 'branded' systems.
I have 2 PC's in my office these days....this new one I am typing on, which is the dogs balaerics, and another which has been my main PC for almost 10 years. Imagine getting 10 years out of your PC, and only adding a little RAM and a PSU in 10 years (had a dirty power cut once when not adequately protected).?
Now, I am not trying to sell you anything, I am merely trying to save you wasting your time in this thread and torturing yourself as to what to buy.
Take £400, look around, and buy the best SPECIFICATION you can get - not necessarily a particular brand !!
Disclaimer.... i have never mentioned Advent above, as I do not rate them worthy of the wear on my keyboard..... but thats a personal opinion based upon years of repairing PC's 
