Have you tried booting off a USB stick or LiveCD? Something like the
Stealth Surfer that we recently reviewed might be an easy solution, if they haven't locked down the hardware, or you can try to follow some how-to guides to get something like Knoppix to boot off a USB thumbdrive. Knoppix (et al) also obviously have LiveCD ISOs that you could burn and try to boot from...
For that matter, does GPO prevent inserting a usb drive in Windows, and/or executing software from the drive? You can get browser variants built to run self-contained on a thumbdrive, possibly in conjunction with something like TOR, if that's possible.