You can take two approaches. The easy one would be to do a repair installation and let the registry be rebuilt. It would leave programs and data intact and would not take that long. The better way, IMO, would be a scratch re installation. This gives time to assess your mom's needs, discuss it with her and eliminate unnecessary programs that take up space and bog things down. As well, you might open the case and clean out the dust in cooling fans, etc., to keep the processor operating at it best speed. You will need the disk and product code and will need to reactivate the OS. As well, there will have been a lot of critical updates that should be installed. A broadband connection is the only way to get this done. If your copy of XP is not SP2 and you can make a slipstreamed copy with the service pack in place, that would save a lot of headaches and time in getting back in service. Ideally, I'd say to do this on a new HD rather than the old one. That could eliminate the need to back up documents, pictures, etc. onto other media. Good luck.