New Seagate drive not recognized . . .

[Ken Sp.]

What are the jumpers set at Master or Cable Select?
Does it match the 20 GB.
Be careful---if you format the drive in a Mac or an external enclosure that doesn't support larger drives--It is a PITA to regain the lost space.
The larger drive should show up and mount even if the case doesn't do large drive--just don't format it.