I want to buy an external hard drive to backup my laptop. I only need about 100 GB’s and would like to know where to find a cheap name brand?
Also whats the difference between
Firewire
USB
USB-Ethernet
USB-Firewire
what should I be looking for? I have a Toshiba laptop.
Western Digital is undoubtedly the best brand in the market for external drives. If you are using an updated OS like Windows 7 then certainly it wil bestow you with the best experience.
For the price range, you’ll get the best value with a USB model (it’s slower than Firewire but it’ll do the job).
As for models, their all about equal in price these days. I recommend Seagate or Western Digital. 
Firewire is the current speed champ, but USB 3.0 is coming and will put an end to that. If your laptop doesn’t already have a USB 3.0 compatible port, you needn’t concern yourself about it. (hint: it doesn’t)
USB 2.0 is slower than Firewire
USB - Ethernet indicates that the drive supports both USB and network connections
USB - Firewire, again, supports both
Before you run out and get a firewire drive, make sure you have a firewire socket on your laptop.
WD has a number of nice externals out there, but I’ll leave the researching which one you want to you.
Further to what rushiku says, Firewire ports are relatively rare still on most Windows laptops (and are often a little bit more expensive on external drives), whilst pretty much every laptop/computer will have USB ports.