The Winmark is a good indicator for a drive's real performance, as this benchmark simulates real disk accesses.
HighEnd Disk Winmark 99
I prefer the High End WinMark to the Business WinMark, as it seems to be better related to practice. The amount of data that the benchmark and the drive have to handle is much bigger.
Here we have some real surprise: The WD400 is even able to beat our performance champion, the IBM DeskStar 75GXP!