I'm reinstalling winXP on my aunts computer and she has a copy of winXP home, but as always, can't find documentation or paperwork of any kind, so no serial number.

Can another serial be used for her disc? (considered using mine but I'd rather not)
If I used another serial would it limit services she could use, such as windows update?
Would it cause any other difficulties? (I don't want to be called over cause X program won't run/install or whatever)



[now that I wrote that it sounds like it falls into a grey area. I'm not asking for anything bad, just info]