Seems Office Starter 2010 (cut down Word and Excel) can be installed onto a USB stick to carry around. The only version of Office that can be installed thus. Free but Ad supported.
http://www.intowindows.com/how-to-run-m ... -from-usb/
Type
Office Starter To-Go Device Manager 2010
in the Start Menu
after you have first installed Office Starter in the normal way.
