I only ask because I have moved away from working on home/personal machines due to the "you touched it last" factor. But I know someone with a gateway laptop (1 year old) with a botched XP install. He asked If I'd wipe it clean for him and start from scratch, otherwise he would take it to CompUSA and have them do it.
I ho-hummed about it and finally then said OK. We haven't work out a price yet, but I've always charged 50hr for side jobs. But since i don't have to be present for most of the OS install I figured I might flat rate this job. Was thinking $125 to $150.