I would also highly recommend the DB35 model. It is very quiet. It's definitely worth the extra cash to me. I figured I had already spent well over $1000 on my S3 - what's another hundred to make the thing quiet? LOL
With discounts, WeaKnees 750GB pre-formatted was $444 shipped for me. I installed it, but WeaKnees will also install for you for a price. If you go completely DIY, I would still get the Seagate DB35 -- I can't hear it at all.
What kind of discounts did you get from Weaknees? Better, how did you get the discounts? I just visited their site and they show pre-formatted 750GB for $499. I did not see any discounts.