both seagates and WD have exceptional 750gb models
you can't go wrong
i would recommend seagate due to the 5 year warranty compared to 3 and the 32mb cache compared to 16mb
I have a Seagate 750gb (I don't think it's 32mb cache though) and it's great. I love Seagate drives and would recommend them over WD. Be careful though. I've read some stuff that says some drives over 500gb are having problems due to the way they write data to the platters. I haven't had any problems, but am keeping my data backed up just in case.