As a follow-up about portableApps, I also just read about a free program called mojopac found at mojopac.com. It is a virtual workspace that is similar to portableApps, but it creates an independent environment on the host computer and is run from usb devices and ipods, etc. I just installed it on my 2.5 usb harddrive and it is pretty cool. What is interesting is that I inserted my usb flashdrive where I had installed portableApps and it will run the portableApps program too! Check it out!