how to use an external HDD

I am getting an external HDD 1tb. I would like to know how to properly format it, and get it ready to run with the homebrew. I would like to know how to run games off the HDD for the emulators instead of storing it on my sd card. A friend of mine advised me to get one so the games will run smoother. How would I go about doing all this? Storeing and running off the HDD.

FAT is probably best, all emulators should support it. Some now support NTFS, but not all.

Thank. I've also been wondering if there Is a NDS emulator? if so, will I be able to challenge others online via the wifi or is that disabled?

There is an NDS emulator, but I can't remember it's name. And I don't think it's finished, but it should be able to boot at least some games I think.

DeSmuME Wii is a DS emulator but as SifJar said it's not finished and is not for all games.

I just got my new external HDD and i'm trying to format but it only says "exfat" and "NTFS(default)" Then it has application unit size. I haven't formated, it says on the box ready to plug and play, i've obviously put it on the comp. to format but thats as far as i got. Not sure what to do next.