Lee,

Seagate makes a 750 gig drive for about $350, and you can get an enclosure for about $40 to put the drive in.

However, if you're storing large amounts of data, i VERY highly recommend the Terastations over an external drive. There's a little known but documented bug in Win XP and 98 (not sure about Vista) that can cause corruption of the directory on the drive with USB or Firewire external drives when copying large files to the drive. We had that problem about 7 times over the past couple years before I did the digging and found out what was causing it. Data recovery software we use (getdataback from runtime.org) will get the drive data back, but it's not worth the hassle in my book.

Plus... if a drive on the TeraStation dies (and you're set up with RAID-5), you can still access all your data... you just replace the bad drive, the TeraStation rebuilds the missing info to it on the fly, and you're good to go.