I have a 2005 Jamis Coda, bought in 2007 and I have 10,000 miles on it. I was thinking about changing the bottom bracket out, to a integrated spindle with the external cups. That way, I can use any cranks that I would like to use, in a 48/36/26 configuration.

Am I better off using a new BB that I have now, which is a Deore Octalink with a splined spindle . I thought it may have a better seal than the one with the external cups.
Thanks for any replies.

Although the spindles for the external-cup BBs should be stiffer, I'd bet you wouldn't actually notice a difference while riding. If you can find cranks that you like for the same price, I'd probably stick with the Octalink on grounds of not having to buy a new BB. Of course, replacement BB costs and availability might change by the time you need to replace your new BB or crankset.