New
#71
First of all I'd recommend you to call off the purchase, save a few bucks and get the drive (plus warranty) from Amazon, which looks like a more trustworthy seller as well. Seagate Momentus XT 500GB @ 7200rpm from Amazon
The Ubuntu looks great indeed (much better than Mint IMO) but there is some crucial software for me that totally makes me to stay away from it (MS Office and iTunes), as well as other software/keyboard optimizations.
The 2nd-gen Momentus XT has really good reviews, learns pretty fast on how to speed things) and seems to be pretty reliable. BTW the older gen had a software issue, I think, so it wasn't really the hardware's fault. I hope it serves you well!