if I'm understanding right,
a WinXP COA is the long number on the label
and costs at least £15 on ebay.
And that is needed to run windows on a virtual machine,
to update and patch it and go online?

Can this COA be shared between different virtual machines?

I believe we cant share it between different physical computers
because it looks at the hardware and checks that its the same as when
registered.

Am I understanding correctly?