If you are having problems staying connected to the net that is probably a problem with your ISP, not with XP. There used to be a number of programs that you could run that would ping your ISPs server periodically to keep from timing out, dont know if any of those would run on XP tho. Some people have said that if they have their e-mail program check for new e-mail every 5 or 10 mins that solves ISP timeout problems.
I am on cable so I do not have that problem, also clean installs of XP seem to have alot fewer problems than upgrades or full installs over existing OSs.