What's the Difference?

[Xein]

I'm looking at a couple of HDD's and just want to know the difference between;

WD "Western Digital Caviar Green 1TB SATA-II 64MB Cache 5400RPM" £44.99

Samsung "Samsung SpinPoint F3 1TB SATA-II 32MB Cache 7200RPM" £44.99

WD "WD 1.5TB 3.5" Hard Drive - SATA-II 5400rpm 32MB Cache" £47.99

Just want to know what the speeds are like between them and how much difference the Cache makes by having either 64MB or 32MB.

Thanks