HDD has an average life of 3-5 years (exclude any Enterprise class HDD) with daily usage (plug/unplug, read/write), so it's a good idea to back up your ext. HDD too.
i bought mine 2 days ago at best buy...WD Passport Elite 500 GB on sale for $125...
my friend's been using her WD one for over a year....she said she had to change the cable once but other than that so far so good...so i just bought mine...i think sale's over now tho...
Lacie are good drives, but many of the AC adapters are defective. Pretty much the tech support at Lacie knows me caz I have to call them to get quite a few AC replaced over time.
About brands, I avoid Seagate after their 7200.10 and 7200.11 drives. I am using 2 WD Blues (750GB and 500GB), Seagate 7200.12 (1TB) in my desktop. My iBook and Toshiba Portege and Dell are using WD Scorpio Blue; WD Black on Macbook; Fujitsu on my older HP P4 laptop. My DNS-323 NAS have a mixture of Seagate 5400.6 (250GB) and WD Blue (500GB).
For the most reliable SATA drives I've used, WD REII and WD Black... and also the Intel X25-M 80GB (SSD)