I have a few programming classes at school (we're learning Python) where we use rather old hardware. They run Windows XP, and usually they all somehow have a few issues (no HDD at boot, unexpected reboots, permissions errors on user folders, and so on)I don't like bringing my laptop, so instead I was using Ubuntu on a live-usb, but sometimes, I wasn't able to download a few libraries (the school seems to be blocking a few URLs). Last time this happened, I X-forwarded a python IDE from home to the school computer from within the Ubuntu Live-USB by SSH, and it was very smooth. Both Internet connections were fast enough to make the experience look like I was using the software locally. From home, my Debian-running computer was able to download all libraries I needed, and any frustration was gone.Is there any sort of live-usb running linux that has the minimum software required to properly run an X-forwarded SSH session? I don't need a whole UI like Unity or XFCE. Just a Terminal prompt and an X window manager supporting X-forwarded windows would be perfect. 
Live USB with just X-Forwarding and SSH abilities
distribution choice;live usb
I'm not sure why you don't use the Ubuntu one you already have since that seems to work but you can find great information on Linux on USBs at the aptly named http://www.pendrivelinux.com/ site.The classic one suggested for this type of thing is Damn Small Linux. It actually has a window manager (FluxBox) but it is extremely light and, well, damn small.