Yes, you can do it with gparted.
But, it will take a very long time (600GB? Hours, if not days.)
And, very big chance of losing data.
It might well be quicker to drive to a store, buy an external drive, and copy the data onto that. This would also give you a slightly better backup, because backups on the same drive are not really backups at all.
Last edited by SecretCode; 10-21-2011 at 01:22 PM.