backup XP VM to ext drive & transfer sync w/ Windows PC?

[chicken guy]

Before I bake this cake, I need some help with the ingredients, please.

What is the best way to backup, transfer and sync info back and forth from a Macbook 10.5.8 with Virtualbox of XP to an external drive to be used on a WIndows computer elsewhere.

I have a Western Digital 500GB My Passport Essential portable hard drive.
I'm suspecting some kind of partition on the drive but in what format?

The software ingredients I'm figuring for file compatibility are as follows:
NTFS for Mac, to allow transfer from Mac to Win sides and/or
MacDrive to allow Mac files to be readable on a separate Windows computer from the portable drive?

for backup utility: Time Machine, Super Duper, Carbon Copy Cloner or Bacula?