OEM Info Tool is a free tool which allows you add or modify the OEM [ Original Equipment Manufacturer ] information in windows 7, it works perfectly with windows 7 and vista both.
Please Note: OEM Info Tool must be run with administrator credentials because it needs to make changes in the registry as well as copy the logo file to the Windows folder.
This is how OEM information looks like before modifying on my windows 7
[ click the image above to enlarge to see in full size ]
In order to change the OEM info, first download OEM Info Tool and run the tool and Add the new OEM Information you want to add
click Change button to the replace and add the new OEM info you have specified above. After changing the OEM information, you will see the new OEM information in My computer >> properties. [ as shown in the image below ]