Green power drives are suppose to save power and produce less heat. They save power by parking the read heads more, slowing the spindle further (or stopping the drive entirely). This is good for external drives (since many external enclosures lack fans or have poor ventillation). However the downside to this is, more wear. Therefore for internal disks you want the maximize performance, you would need the Black drives. They have faster spindles, more cache, and produce more heat while using the most power. Blue drives are essentially Black drives that are slower, but use the same amount of power.
The power consumption difference between Green and Black drives are minimal; so for a consumer computing environment, it's pointless trying to save a 10W of power and losing a lot of throughput.
As with my hard drives drives, I have Western Digital VelociRaptors. Back in the day they were excellent (they still are), but they are loud, power hungry, and expensive. You are better off buying 2TB Caviar Black for about 2/3 the price of the VelociRaptor; if you wish to have speed, consider a SSD for your boot volume.
Anyways, my setup consists of 3x 120GB OCZ Vertex 2 SSDs in RAID 0 for boot; this is a fast setup for boot, but it is pricy; this setup gives me 360GB of usable space. If you're budget allows for it, it definitely worth it. Mind you, don't bother with more than 3 SSDs in RAID 0 since that already saturates the limit of the Intel ICH10 chipset. If you want more than 3 SSDs, you much get a hardware RAID card.
For my media, I have that stored on my 4x 300GB Western Digital VelociRaptor in RAID 5. This is a fast setup as well and was my original boot volume setup; it has terrific sequential read and write performance, and respectable random access performance among HDDs; RAID 5 on the Mac requires a hardware controller, so this is expensive as well (a good one is $500+). Again I would pass on this setup nowadays since for the price of the current VR drives (which are 600GB for about $250) is more than the price of 2TB drives by quite a margin. SSDs do not match the capacity, but the performance far outmatches these drives.
For Windows and daily backups (not Time Machine), I have a 2TB Western Digital Caviar Black for this. It's fast, not very loud, and runs pretty cool. Again this is drive I would recommend if you are looking to purchase drives.
Finally for Time Machine, I have an external RAID 1 solution with 2x 1.5TB Western Digital Green drives. Slower drives, but it's in an external and it's quiet.
If you didn't feel like reading that:
1) Skip the Green power drives; get the Black drives for best performance.
2) Don't bother with VelociRaptors and other 10,000 RPM drives; consider an SSD instead if you have the budget.
