hi, i have a x120e with windows 7 home premium. the sticker is under the battery with the activation code. i replaced the hd in my with a 64gb sandforce 1200? and had to reinstall.
1. Download windows 7 upgrade iso for the version you have a key for.
http://www.mydigitallife.info/downl...cial-32-bit-and-64-bit-direct-download-links/
2. find the official microsoft usb-dvd tool to put the dvd iso on usb. it is always hard for me to find the tool.
3. you have to install same windows over windows, wiping all your files, so backup.
4.try and register it with microsoft. if you have trouble you might need to regedit to change some mediabootinstall? entry from 1 to 0 to indicate full install instead of upgrade and do a rearm.
it isn't against micro's license agreement. if you have trouble, you always have 120 days to register, 4 rearms 30 days apart.