Is the firmware for the PIX 501 and PIX 506 the same, or is there a special version for each unit? I've got an old PIX 506 running v5.1(2) that I'd like to get updated to v6.3(1). I have a new PIX 501 and the product CD with the firmware images. It would be nice if I could use it to upgrade the PIX 506. Besides, for some reason, Cisco has all their firmware upgrades under lock and key. Even units under warranty have to open a TAC just to get somebody to post the image for individual download. So how 'bout it - is the firmware the same for the 501 and the 506?