Here are some website for redeem customer free upgrade offer:

Toshiba:

http://www.mytoshiba.co.nz/web/products/windows7/upgrade/2.aspx

HP:

http://h20426.www2.hp.com/program/windows7/upgrade/ap/en/index.html

ASUS:

http://event.asus.com/2009/windows7/

Sony:

http://www.sony-asia.com/section/win7rel