usbnetworking in OS2008 works, but I only got it talking with my linux box at home - WinXP at work resists (did already with OS2007), not sure why. Maybe there is somebody around having used XP successfully for this?

Possibly you not having administrator status on the box may also be an additional show stopper.

Worth mentioning on the iT-side for OS2008:
- insmod usually needs to be done twice (error message at first try!)
- usb0 is already configured, just "ifup usb0" as root
- change /etc/resolv.conf appropriately for DNS lookup
- to use the connection from hildon applications, use dummyiap

Did you ask the IT guys if there is a possibility for wifi guest access, isolated from the internal LAN? Because more often than not, you don't want to access your workplace computer or any other company computer, you just want internet access from the tablet. And even paranoid companies sometimes have such a guest access point.

cheers

Rupert