Xp Home v XP Pro - For the home user who isn`t interested in networking stick with Home. Even if you were interested in networking a handful of computers Home will still cope with it.
I have XP Pro but I connect up to corporate company networks occasionally that run domains. I also have several computers with XP Home that are wirelessly connected. £50 isn`t much except when you haven`t got it or could use it better elsewhere. My advice is the latter!