HARD DRIVES

So I'm getting a third hard drive, and was wondering whether there is a big reason to get internal over external.
I want to use it to store shit that I'll be using often, not as just backup.

>>2
Yes, 2.5" drives are quiet.  But they are also low capacity, expensive, and SLOW as fuck.  Disk I/O is the worst bottleneck in any system.  Improved bandwidth is the same reason to go for an internal drive instead of an external.

>>1
500 GB Samsung SpinPoint T.  SATA-300, 16 MB cache, as fast as WD's 10,000 RPM Raptors at 7200 RPM temps, quieter than any Seagate, relatively inexpensive, low power consumption.  Nobody should be buying any other SATA drive right now, unless they need Seagate's 5 year warranty or want to go perpendicular or 10K RPM (or U320).