The first link is a brilliant "basic home computer" for much less than you're thinking of spending. It doesn't come with a monitor but these are cheap to buy separately and if done from a shop, saves you delivery fees : monitors are bulky and heavy to post.
If you use it for anything more than browsing the internet, downloading, word processing (i.e. anything processor/memory intensive) then it would benefit from a memory upgrade to 512MB instead of 256MB:
http://tinyurl.com/58zh7
Even then it'll still cost less than �500!
Also, at Dell there are 2 days left of a "free delivery" offer on Dimension Desktops (the page below shows the Dimension 3000) which also turn out cheaper.
http://tinyurl.com/3vy8v
If you do anything to upgrade this (add a floppy drive, add more memory etc.) then you will be far far cheaper to do so separately (buy it from ebuyer.com) rather than add it onto your Dell package (although this may invalidate any warranty).
To cut a long story short, you can get a great PC by spending less money. If you spend �500, I'd expect an awful lot from a PC, much more than a "basic home computer".