If you have the "Member Passport to Savings Coupon book Summer 2008" from Costco, it has a coupon for $30 off the 1 Terabyte Western Digital one and that brings it to $199
Coupon says it's only good June 16-22.
I have the one you showed from Amazon, the 500 Gig Western Digital My Book, and am real happy with it except that I'm running low on space. I'm sure I could solve that by deleting stuff though!
I have a laptop and since I don't go mobile very often, I find it just fine to have a non-portable EHD like the My Book. Since it has it's own fan and everything, I think it's a better choice for desktop computers. The smaller portable EHDs just plug into the computer and don't need an electrical plug which is great for laptops that go mobile. Actually, maybe I should think about getting a portable EHD now that I think of it! LOL