At first, I backed up my Win 7 OS, I could find my WD drive.
After that, I used WD passport to back up Win XP from another PC with the disk size of only 25GB.
I do not have any problem in booting Win 7 from it at the new PC after that. However I find that the WD Passport drive is now default at the XP drive.
I could not find my Win 7 OS drive which has a larger disk space of over 450GB.
May I know how to change by default back to Win 7 OS whenever I plug in WD Passport ?