Woot is a very legit site. They sell one item per day, for really cheap. $5 shipping. Occasionally they have some pretty crazy steals, fun events like 2-For-Tuesday, Woot-Offs, Bag-O-Crap, where you get a bag filled with random things, from batteries to bracelets to LCD TV's to giant piles of tangled cables. You should definitely visit the site daily.
However, this deal is not hot. it's a respiffed (refurbished) hard drive with a 180 day warranty. Would you trust your data on a refurbished HDD? Spend the extra $30 and get a 5 year warranty.
Even though its refurb, its cheap enough that you could make a super cheap RAID setup, and even if one failed, no biggie, you can just go to standard configuration or buy another.
It's not THAT great of a deal unless it is free shipping, then it's an OK deal. Just go to pricewatch and look up the 500GB sata's. You can get a seagate shipped from known websites for $59 everyday.