5 - 30 Minuten
I had volume structure corruption that would not go away even after a clean install, so I suspected my HD was faulty, even though it passed basic tests. I determined later that in fact I had copied over preferences files from my backup to the new install, which had carried the corruption with them. So now I have two solid hard drives with no hardware problems. I used the silicone USB enclosure that came with my drive replacement kit to house my old drive, which I'll now use as a backup drive.
It was very easy and went smoothly. It was even easier than when I replaced the HD on an older Macbook Pro a few years ago. I ran TechTool Pro on the new drive, and it found no bad blocks nor any other problems. I was always trying to keep from running out of headroom with my 500 GB drive, but now with 750 GB I'm more at ease.
Take a deep breath... especially watch out when you pull the hard drive out of the computer, since the thin ribbon cable is still attached and it feels fragile. I didn't break mine, but I almost gave it a tug that could have been disastrous.