I kind of agree with Binos, but it looks like Richard has picked a pretty good system there. You could do much worse
For the last couple of years, my personal view has been that if you aren't interested in games then the best buy is the bottom of the range model - or, even better, to try and track down the one that's just been discontinued, because that's usually been heavily discounted from an already cheap price (recently got myself a great IBM R40 Thinkpad that way for not much more than £300). My main 'work' desktop is a Dell 2400 that cost just under £100, new and delivered (no monitor though). It needed some more memory and has a hardware spec that will give Richard nightmares, but it's still far more powerful than it needs to be for what I use it for (MS Office, MindManager and Lotus Notes).
If you buy a bottom of the range system you may need to boost the memory a bit (I agree with the others, 512Mb is a minimum) or swap out a couple of components, but that's cheap to do and if you're a novice there are plenty of places that will do it for you - track down your local independent computer shop, they're usually good for advice on whatever you want to do and they'll fit it too.
And if that all sounds like too much trouble, then you wouldn't go wrong ordering the system Richard picked out. Mesh are a good company.
edit: one further comment about Dell - I agree again with Binos that they're a good way of finding out a benchmark price and, at times, they can be stunningly good value. However, the quality of components isn't great and i'm not impressed with their customer support, so i'd hesitate to recommend them.