Now you're advocating the violation of Microsoft's Windows license? There is only one live CD/flash version of Windows that's legal according to Microsoft, and that's Microsoft's own WinPE, available only for enterprise use.
Yeah...one license per install:
"Also, according to the Microsoft EULA for Windows XP/2003, a user may not simultaneously use more installations of these operating systems than the user has license(s) for. This also goes for BartPE. In practice this means that the user may not use, for instance, a single license installation on one computer while simultaneously using a BartPE installation (created using that license) on another computer."
Got that? If you use the same copy of Windows XP to install to the USB drive, then you can't simultaneously run your home computer and another from your USB drive simultaneously.
So, you pay for another Windows license to install it on a USB drive with software written by an unknown third party.
Sounds good to me.