Stresstesting harddrive for reliability, for how long?

[Santa Claus]

Hi, got me a 640gb western digital blue harddrive the other day and is stresstesting it for reliability.
Maximum harddrive temperature i have seen is 51celsius.

Bart's stuff test v5.1.4 have been running for 1 day 1 hour and 51minutes.
Total written data 1.7TB
Total read data 1.2TB and rising.
Max/s 107.9Mb(written) 109mb(read)
Avg/s 65.9(written) 16.8Mb(read)

Blocksize 256Kb is OK
Verbose mode
Starting on file'W:\bst263.tmp"
Volume "W:\" size=596.2Gb
Operation: normal
Sequential Write
2368312 blocks (578.2GB) written (sequential) Avg Xfer 83.4Mb/s
Sequential read with compare
2368312 blocks (578.2Gb) read (sequential with compare) Avg Xfer: 85.9Mb/s
Random Write
2368312 blocks (578.2Gb) written (randon) Avg Xfer 20.4Mb/s
Random read with compare
2368312 blocks (578.2Gb) read(random with compare) Avg Xfer 14.7Mb/s
Half stroke write
2368312 blocks (578.2Gb) written (half stroke) Avg Xfer 65.9Mb/s
Half stroke read with compare

I would rather se the harddrive fail today and not 3 weeks later when i have 500gb of data on it, thats the reason why im doing this.
Roughly how much stresstesting is needed to se if its a flawed harddrive or a harddrive that will work for the next couple of years?
Regards