I have a notebook which came pre-installed with Windows 7 Home Basic.
Should I buy an upgrade,retail or oem version?
I want to buy Home Premium for full Windows Aero support and the ability to change Theme which Windows 7 Home Basic does not have.
Cheapest option is the Upgrade, but it will remain locked to the Laptop as the installed OS is OEM. Same applies to the OEM full install version. If you buy the full Retail version you will be able to use it on any other machine in the future.