I asked a similar question a while back but this is a bit different.

I have a drive with ext3 that was my old /home drive.

When I moved to 9.04 I went with ext4 and just link to my old home drive.

My old ext3 drive is becoming unstable so I want to back it up.
I have a 500gb ata drive (unfortunately not a sata drive) that Im going
to wipe and put 10.04 on. I want to move my data from this backup drive
Im going to back up to, to the new 10.04 until I get another hd as a
backup drive.

My question is, I know there is some issue between ext3 and 4 and I dont
want to get into a bind. What would be the best format for moving
between all this to get to where I want to be?