My second hard drive just failed!!

It's a Western Digital Green 1Gb SATA; I've been using it as a second hdd for storage, for about 1.5 years.

I can't see it with Explorer.

Error messages:
"E: is not accessible. Data error (cyclic redundancy error)"
and
"You need to format the disk before you can use it"

This happened suddenly, today, out of the blue.

When I go to Disk Management, after a long time it says that the drive is RAW and healthy!

I ran a test with SeaTools after rebooting and it shows that "test failed" and some codes.

Here are the images:
http://box.c.yimg.jp/res/box-s-m5p45...13639665552443

http://box.c.yimg.jp/res/box-s-m5p45...13639665568395

http://box.c.yimg.jp/res/box-s-m5p45...63966558102131

The hdd gave little signs of problems before (like cyclic redundancy error), so at that time I ran check disk at boot, but it never happened to fail..

Please help, what can I do?