USB Drive permissions -owner questions

Not sure if this is right place to ask this.

I have a dual boot system with 2 external usb drives.
openSUSE 11.1
openSUSE 11.2 M8 ready to upgrade to RC1

my external drives are:
120GB Maxtor with a label of disk formatted as ext3 (used for backup
of the openSUSE 11.1 system.
owner:root group:disk permission 775

1GB MY Book drive (Seagate drive) 2 partitions
partition 1 100GB Windows Fat Used by Win Xp as guest on
owner:root group:users permissions 775

partition 2 400GB formated ext4 used to backup openSUSE 11.2
owner:root group:root permissions 755

Just added second partition yesterday. went to add folder but its
greyed out for user. Other two drives are not.


  1. Is owner:root group:disk correct one to use? (User xxxx is
    a member of group disk).

  2. Is 775 correct permission?

Thanks for any pointers and help!!