OEM is sold only with certain hardware. Can not be sold separately. Can
not be used to Upgrade older Windows. Can not be transferred to another PC.
Must be sold with the PC when the PC is sold.
However, OEM rules completely change when you have an OEM Recovery CD. This
can only be used on the PC it came with or was made for. May not be able to
do a repair re-install (it may wipe the PC clean and restore the XP to
factory defaults.) Must always follow the PC that it is to be used with.
Does not do upgrades of older Windows
Also, OEM versions are not entitled to technical support from Microsoft.
You must contact the place where you purchased it
Retail versions can be used the upgrade older Windows. Can be transferred
to other PCs. Can be sold separately. Microsoft will offer direct
technical support (free amount of time and/or fee based).
Both version can be used to completely re-install OS on the same PC. Both
can also do a repair re-install (install on top of an installed version so
as to fix files.) Both are subject to the same activation rules: every 120
day, or more, Internet activations should succeed. Both needs to be
activated. License can only be used on ONE PC.
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