I bought two of this size disk a couple of months ago. A seagate 7200.10 500 Gb, and the 500Gb Wester Digital model (can't remember the exact name sorry). Both are SATA-II (being used on an SATA-II port). Can't say I can tell any speed differences between the two, but having plugged each on in on its own to compare noises, I found:
The WD to be noiser (and annoyingly whiny) in operation, but quietish head seeks
The Seagate to be near silent in operation with very loud head seeks.
Of course this could be influenced by the relative positions in my case, the WD was at the top of a Mountain Mods UFO and the seagate at the bottom.
Oh and the WD was a bit cheaper.