I would always go with external power. The USB ports on the Wii only just have enough juice to power a hard drive, this make the power supply work harder and therefore run hotter a more prone to burn out. Whilst this may be fine for testing purposes, for long time gaming it will kill your Wii.
I have tried with success
500gb Seagate Freeagent
1Tb Seagate Freeagent
And am currently using a 500Gb seagate 3.5" drive in a Allcam Drive Dock. Its one of those external docking stations that you slot an SATA drive in the top. It has Esata and USB connections, when I conect it to the Wii I use USB, but in the PC I use Esata because it handles data at 3Gbp/s (USB is 480Mbp/s) so makes putting games on the drive way faster on the PC than a USB connection.
Last edited by Captin; 04-26-2009 at 06:53 AM.
the heating issues is why i only use usb loader to rip games to put on a disk (wiihttpd takes waaay too long)