OK, OK, I admit it! I ignored everyone's advice.
I did listen, honestly!! But when I thought about it, I just wanted something a bit faster and with enough memory to keep me doing what I've always done on PCs, for a few more years. The rest, for me, was irrelevant.
So...I bought the PC World special sale deal off their website. £429, for something that as far as I can see is about £600 anywhere else, and will be fine for what I want - I hope! It even comes with a 17" monitor, which I don't need, but have found a home for already - even getting paid a pittance for it. And not a whisper of extended warranties. It will hopefully arrive within a week.
Anyway, thanks everyone. Dropping in here now and then is quite an...education. Speak to you all again if anything goes wrong with my new PC - hopefully not too soon!
And Stormy, that webcam sounds like fun - I want one!