well, if you're like me, with something like windows 98, upgrading to xp (home or pro), if you upgrade, it will keep everything, but will give you a detailed list (which i found so useful, and like i said, very detailed) of programs and hardware and things on your computer that may need to be reinstalled, or updated, drivers that need replacing, and programs that need patches to work with xp.
Also, if you have a good connection to the net, try running Windows Update and it will find some drivers that may have needed updating to work thanks to changing to XP.
Very useful..
after that, just do aa bunch of tweaks to set your pc up the way you like.
If you choose the feature i believe is 'Full Install' or something, i think it formats your harddrive, or lets you make a partition to create a dual OS system. Upgrading is a lot better IMO if you want to save all your files and stuff.
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