That's a pretty low-level PC you're being offered there, though I suppose you could do worse for £350. But if that's your budget, I'd have a look at the Dell Outlet - I've just had a quick peek and you could have a bit more RAM and a bigger hard drive for that sort of money.
Contrary to the previous post you do not need a pentium4 processor if the computer is to be used for documents and the Internet. The spec and memory are more than enough for word processing and t'Internet. A Pentium processor will make no difference at all. You do not need a 200Gb HD for this use and if you do need extra storage you can buy an external HD which is a much, much better option. However I would check out Dell as for that price they were selling Vista computers with 19" TFT screens. If you are suing it for WP and Internet don't get hung up on HD size and processors, you will notice no difference.