Possible to boot into an ISO located on a usb drive?

[hazard666]

Well I recently purchased a 4gb usb drive and love it. Can stuff miscelleneous junk on there and bring it along with me. The only thing I don't/didn't like about it is that I couldn't boot from it. I however fixed that with the HP usb drive formatting/boot "trick" and now the drive is able to boot, but the way I have my files sorted on the drive is via categorized folders. What I would like to do is boot into like an Ubuntu ISO located in the Operating Systems folder. What would I have to do be able to do this? I guess basically what I want to know is; how do I boot into an ISO like a normal cd does?
Thanks for your help in advance.

EDIT: I am currently running XP Pro if that matters.

 

[magomago]

well if you want to boot into an iso that seems a little difficult.... because an "outside program" that would wrap around everything would have to be able to create a virtual drive, and mount the iso....

is it possible using an ubuntu install CD to install straight to the USB drive? That way everything would be setup on that...

 

[hazard666]

I was thinking of that but I would rather but use up all of the space on the usb drive simply for the installation. I would rather just install from it like a cdrw or a bootdisc. I can just as well burn it to a cdrw, but this seems a lot geekier, heh.

 

[hazard666]

What if I wanted to mimick a livecd and copy its contents over to the USB drive and tried to boot into a directory of the drive? Would that be possible? How would I be able to point to the linux live cd portion of the directories?