Too long, unless you formatted with the spare superblock according to Roger's site.

I think it's between 10 and 20 minutes.

Also, since you've a dual drive, you should be able to run the fsck on each drive in parallel. Make sure fsck pass numbers are set up in /etc/fstab ( / = 1, and everything else = 2) and add a "-A" to your fsck, "fsck -faAy" fsck is smart enough to not check multiple partitions on the same drive simultaneously.

--Nathan