check there are no options in BIOS for turnin off eSATA. I thought eSATA runs off the same chip as other SATA devices so I would have assumed support was already there. but double check that there are no port options that might disable it.
also if you could check the eSATA on the Nexstar on a different computer so eliminating either the enclosure or ur notebook as the problem.
Thanks, based on the advice provided, it turned out to be the esata port on the brand new ASUS notebook (4 days) . I have returned to place of purchase and was given a full refund, after they validated the port was not active. It did'nt even show in the BIOS. The Vantec enclosure worked with other esata computers in the store.