I picked up one of the Western Digital MyBook Essential 2.0 1TB USB2.0 dives from OC and I am happy with it
Pro's
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Fair bit of storage!
Nice Design (keeps cool)
Quiet (Compared to my other external drives!)
Diag tool (Not tested other bundled software)
Power Management:
Drive switches its self off and on again with the PC and in my case when Vista media Centre PC pops in and out of sleep mode. Also when the PC is on the drive goes into a power save mode after x mins (I have disabled the option switch hard drives off in Vista power save, so I presume its the drive controlling this? Although there seems to be a bug in Vista that puts secondary drives to sleep even if you set it not too!) Here is what my power meter reads!
Off .2 Watts ish
Power save (PC On): 2 Watts
Active: 7-8 Watts
Cons:
Not many really Just niggles.
Drive comes pre-formatted as FAT32 no NTFS (Presumable for non PC compatibility)
The activity light on the front is pretty, however this is off-putting in my setup as it is next to my TV. (Time for same PVC Tape!) Shame you could not disable this via software.
This is USB only, however it works just fine for me.
There is not on/off switch.