I shouldn't bother! In a machine like that, XP will run so slowly that it will almost stand still! You may however benefit from a re-install of Win 98 provided that you have got all the necessary drivers. I sometimes wonder how fast my own XP Pro mackine would run if I was using DOS Ver 6.22!
Oh for the days that I used DOS 3.3 to run a machine with a 30 Mb - yes 30 Mb hard drive. The drive held a desk top publisher, wordprocessor, spreadsheet, drafting programme, database - and plenty of games!
P.P.