How long does a clean install of Lion take? How long should I expect it to take to do a clean install of Lion on an already-formatted disk? I'm using a mid-2010 15" MacBook Pro with an i7 and a 5,400RPM 500GB hard drive.

(I ask because I think my hard drive is in bad condition, and the installation seems like it's taking too long.)
About 40 minutes or so. I'm assuming a 5400RPM drive, 7200RPM or an SSD would be faster, obviously.