2 - 4 Stunden
I had shortage of disk space on internal 500Mb HDD of Mac Mini, so I planned to install second high-volume drive. I chose WD Scorpio Blue 1Tb HDD (5400 rpm) as a second drive. I'm also planning to replace 500Mb stock HDD with SSD in the future.
I followed iFixit video installation guide on youtube. There are some tricky points, but generally I did it smoothly.
the hardest part for me was re-assembling power unit, motherboard and main body together.
Also, I couldn't tighten back all 4 screws holding wi-fi antenna plate. Either one or another hole in antenna plate is not aligned with the hole in the computer's main body. I tried to align the plate many times, and finally secured it, using only 3 (of 4) screws.
Detaching signal cables from motherboard should be done with extreme care - there is a chance to damage a thin wires in the fan cable. W-fi antenna cable also need some accuracy. It's better to use "spudger" tool from the kit rather then bare hands to do it.
Pay attention when re-installing power unit with AC socket part back to the body. The socket must fit into the hole in the rear black panel. If socket is slightly misaligned , you won't be able to install motherboard back.