Portable OOo on both:PC and USB stick

This situation:
I use OOo on the PC already (XP).
Now I like to take a portable version to work where this programs are not available.
Starting installing on the stick ends in the dialogue "Change, Repair" Delete". This not what I want.
I want both
An OOo on the PC to use and an OOo on stick.
How to do?