Calculate HDD Input Outputs per second (IOps)

If you're looking to buy HDD and you need to know what IOps it can sustain, here is a formula you could use:
IOps = 1000[msec] / (Average seek time [msec] + Average Latency [msec])

For example let's calculate IOps for this IBM SAS HDD
1000 / 4.7 + 3 = 129.87 IOps

Links:
http://blogs.smugmug.com/don/2007/10/08/hdd-iops-limiting-factor-seek-or-rpm/
http://technet.microsoft.com/en-us/library/bb897498.aspx

Disk check running everytime Windows starts

Sometimes you might face a situation when disk check is running at computer boot up and it hangs (probably due to HDD problems) and can not complete successfully, so after you restart your computer the disk check is being run again, so you need to manually cancel it every time to be able to boot into Windows.
In this situation you might want to disable auto disk checking at booting.

To disable disk checking every time you turn on your PC:
Open command promt (win+R, type cmd and hit Enter)
enter command

chkntfs /X C:

(screenshot) where C: is the letter of the disk you're having problem with.

More detailed explanation and causes for this behavior might be found here:
http://www.pcadvisor.co.uk/forums/index.cfm?action=showthread&threadid=231103&forumid=1