Now running FreeBSD 6.3 from HDD

Well, I installed FBSD 6.3 on a 12GB primary partition on the Dell internal HDD and the install went without problems.
Then I only needed to change the FBSD entry in the Ubuntu partition (where the mbr is) for FBSD to

title FreeBSD 6.3
root (hdo,3,a)
kernel /boot/freebsd/loader

where (hd0,3) is the primary partition on the internal HDD where FBSD is stored and a is its root directory.
Thereafter FBSD booted without problems.
Still can't say I understand why I couldn't get FBSD to boot from the usb HDD, though. When I understand a bit more about what's going on here I might try th usb HDD again.

Note that on the int HDD version, I used KDE in FBSD whereas on the VM version I employed Gnome.

To get KDM to start at boot without having to go through a rigmarole of logging in and then starting KDM manually, is different from the situation with Gnome. I posted about this to BSD forums and got this reply which solved the problem.
However, befire getting to this stage, it is necessary to install xorg (pkg_add -r xorg)