Powerswitch thru USB or Parallel port
 

I am looking for a cheap solution to have a (physical) switch which is controlled thru a USB or Parallel port (on WinXP/2003)

I want to switch off an external USB harddrive, which is connected to a remote server, so it is not running 24 hours a day.

You should think that something already exists but I have could not find any cheap solution

I know there is a 8-port parallel switch @ Conrad which could work but I only need one single switch and the included software only works on win9x?!
The APC PowerSwitch, which has a web-frontend, is just too expensive for this sort of thing!

Things like stopping/restarting the HD motor which software just do not work

Not quite exactly what you wanted, but there's a very useful, still very little known software called SwapManager that implements IDE hot swap capabilities under Windows 2000/XP(/2003?): http://www.mobilexperts.com/software.cfm#SwapManager . Thanks to it, I can carry stuff from home to work and back on my hard disk rack every (work)day and have uptimes of over a month. ;)