I didn't realise there was a choice, when reinstalling the Windows xp, between a reformat install and a "layering" install.
I'm trying to connect to the internet using broadband but I'm not having much luck. The provider has gone through many possible reasons as to why it is not working. Now they have informed me that a possible reason is that my pc has something on it, maybe some virus, that is stopping connection using broadband. They have suggested reinstalling Windows xp to see if this helps.