That is really cool. But i don't think im brave enough to do that to my computer, if i lost anything from it i'd seriously kill myself.
1. Doing that won't mess up your hard drive as long as you dont do something dumb like drop it 2. Its a good idea for a server, but a waste of space for your average desktop computer, everything in them are adequatley cooled
I agree with Todd, its a bit unnecessary for even power users. Increasing airflow across the board and having two maybe three case fans to direct the air across the board and out should be all one really needs. If you're into the whole overclocking thing then water/vapor cooling can become more attractive, but its not like you overclock your harddrives...
it really depends how you use your computer, if you were constantly playing games the hard drvie does tend to lag and cause damage to itself