My friend has a system that must be a pirated copy of XP Home. It comes up ad warns that this is not a legal copy. Can I take a legal copy and install over it so he does not loose any data. Will this correct the problem. Bruce
If the legal copy's key code is in use - that's a no go, mostly.
Laptop? Desktop? OEM? Full? What is his system rig & flavor?
If his is a full version, then the reinstall must be a full.
OEM to OEM if that's the case. If yours' is a laptop, full, and your friend has a desktop, full, the overwrite will work with your key.
One key is good for two machines if one is a laptop & the other is a desktop.