@Kurimasu:
My external HDD has its own power supply and I bought it from Amazon.com. I'm sure where you can buy one in the Philippines (but I'm sure they are selling those there).
@PenPusher :
Theoretical transfer rates:
eSATA (3Gbits/sec) > USB 2.0 (480 Mbit/sec) > Firewire 400 (393 Mbit/sec)
Looking at the numbers, one can assume that USB 2.0 is faster than Firewire BUT in terms of sustained transfer speed, a Firewire 400 is fairly consistent with its 393Mbit/sec while USB 2.0 fluctuates and slows down with more USB devices plugged in. Thus, based on user experience:
eSATA > Firewire 400 > USB 2.0