One of my customer's PC's was knocked out by a power surge through the
modem connection. It has an OEM copy of XP home. It is my
understanding that if I replace the motherboard, then she will have to
buy a new OS if she wants one from Microsoft. This basically means
her computer is a pile of junk.
That's not correct. There are two potential issues here, a physical
one and a licensing one:
1. The physical issue. If this OEM copy is one installed by a major
OEM, such as Dell, it is probably BIOS-locked to the motherboard. If
so, it would be necessary to replace the motherboard with an identical
one, otherwise that copy of Windows would not install.
But if it's a generic OEM copy of Windows, not one specifically from a
particular OEM's computers, that's not an issue at all.
2. The licensing issue. An OEM copy is licensed for only use on the
original computer it was installed on, and may not be moved to another
one. For a long time, it wasn't clear exactly what constituted the
original computer, and many people felt that replacing the motherboard
made it a different computer.
However, Microsoft has clarified the situation. See
http://www.microsoft.com/windows/products/windowsvista/buyorupgrade/a...
or
http://tinyurl.com/384gx5
which says,
"You might have to activate Windows again in a number of instances,
such as:
....
You make a significant hardware change to your computer, such as
upgrading the hard disk drive and memory at the same time or replacing
the motherboard in your OEM (Original Equipment Manufacturer)
computer."
Although this page is about Vista, the same is presumably true of XP,
and this clarifies that replacing the motherboard is specifically
permitted.