If you just want to check the disk, you can put it in a PC and boot from the cd from http://www.ultimatebootcd.com/

It has the Seagate Manufacturer's utility ( and lot of others)
It will tell you if your disk is bad. A lot more reliable than SMART.

I use it all the time.

Or you could just download the Seagate util itself:
http://www.seagate.com/support/seatools/