My Seagate 1.5TB Barracuda (7200.11) drive just crashed yesterday.
I am lucky that I was still able to grab all of my data off of it last night after I bought a replacement drive (WD Caviar Black, 2TB).
There is a problem with the 7200.11 drives and the 1.5TB drives seem to be the worst of the bunch.
Sorry for your lost data, but any time a hard drive gives you any sort of warning that it might break down then you should back up data immediately. I've had Hitachis, Western Digitals, Seagates, Quantums, and Maxtors all crash and burn on me. I usually replace 1 hard drive every 18 months or so.
My friends who mix music go through 2 a year.