...Trisquel.. already installed on a 1TB desktop-style HDD...
I don't think Windows has built-in support for the file systems like ext4 and whatnot used in the GNU/Linux world. Maybe there's a third party program that might be usable if you want to be able to access the drive from within Windows. I don't know...
Also, it's not entirely clear to me what's supposed to be on this 18GB USB flash drive...
