I'd just go for the slower SATA II connection.
Saves 32 pounds, and you'll be sure it will work fine, albeit, yes, a bit slower. Would you notice though? Do you boot your system every 15 minutes? Hm, if you odo lots of video processing, it might be of benefit...
And, by the next mobo you buy, you'll feel like you got yourself a brand new harddisk as well...