I have tried several times to run various Linux images inside VMWare, and never succeeded in getting them to "see" the 770 plugged into USB (although the USB printer and removable media did work).

To flash the tablet I always use a Knoppix live CD. Recent versions automount everything in sight (hard disks, NTFS partitions, USB keys, CD-ROM) so you just have to click on the icons... In typical setups (DSL router with DHCP) networking "just works" too, so you have a choice of pre-downloading stuff in Windows before the boot, or once in Knoppix.

Flashing has always been fast and reliable with this method. Each time I waste half an hour trying a new variant on VMWare and then end up doing it in five minutes with Knoppix :-)