i would go for the caviar black, cause the seagate has a very slow accestime (15-16ms), the WD has a acces time of 12ms.
personally i would go for the samsung sping point F3, which is around 80 bucks and has a accestime of 13ms and also had 500gb/platter
so you get both the advantage of seagate and WD for for a very nice price!!
seagate 7200.11 was believed to have firmware issues but both my 7200.11 1TB are alive and kicking for a year now. Even then, I didn't find it justfiable to purchase the cavier black over something that's significantly cheaper (20 dollars is still a lot to a student like me). Now that seagate fixed their firmware issues. i see no reason what so ever to buy the WD.
edit: oh ya perhaps WD might have a longer warranty but don't quote me on that. (still not worth it IMHO)