At the moment I am running Ubuntu 12.10 from a USB memory stick, and I wondered whether it would be possible to save and run any programs I have downloaded from another USB stick instead of the one with the operating system on. I'd like to be able to set the download location in Ubuntu Software Center to the second memory drive, but i don't know how to do this. I can keep the operating system on the one USB and the programs on the other USB, which makes everything much more easier. Any ideas?