I really don't need 500gb. Just need the 320 external. But would like to know will the 320gb version run cooler/quieter than the 500? The 500gb won't be that much faster if at all right?

I have a seagate 7200.10 seagate 320gb and it runs much cooler than the 500gb samsung.

Western Digital My Book Premium ES WDG1SU5000N 500GB 7200 RPM External Hard Drive - Retail

Average Latency: 4.2ms
Average Seek Time: 8.9ms
Cache: 16MB
Dimensions: 2.2" x 6.8" x 5.6"
Features: Easy to set up, easy to use - Installation is a snap because you don't really "install" this drive, you just plug it in and it's ready to use. There is no CD to install; the included software loads from the drive the first time you plug it in. PC and
Form Factor: 3.5"
Interface: USB 2.0 / eSATA

OR

Western Digital My Book Premium ES WDG1SU3200N 320GB 7200 RPM External Hard Drive - Retail

Average Latency: 4.2ms
Average Seek Time: 8.9ms
Dimensions: 2.2" x 6.8" x 5.6"
Features: Easy to set up, easy to use - Installation is a snap because you don't really "install" this drive, you just plug it in and it's ready to use. There is no CD to install; the included software loads from the drive the first time you plug it in. PC and
Form Factor: 3.5"
Interface: USB 2.0 / eSATA