I’m thinking about buying a 500 GB external hard drive to store some of my stuff, but I’m not sure which one to get. I was thinking about going with Western Digital, but they have a ton of models of the same size, so it’s a little confusing about which to get. Does any one have any experience with them and could give me a suggestion?
Thanks 
Well. I have one made by ‘Acomdata’, which I had never heard of, but thankfully it seems of excellent quality and I’ve had no problems with it.
Other than choosing the right model, I don’t see how you could go wrong with western digital. They’re like THE name in hard drives.
Either way you go, it’s a very useful thing to have. Just remember to back stuff up. 
I’ve got a 500GB Western Digital External Elements hard drive. It’s a nice little external drive, and I got it pretty cheap ($169 AUD!!!). Haven’t had any problems yet, although it is a good 30 gigs or so less than 500 gigs. No bother, though. Just one drawback: No power switch. From what I can see, it automatically switches off when disconnected from the computer.
I bought a Maxtor One touch III 500gb external hard drive for $115 at Office depot, it’s done great and it was really inexpensive!
But i found out that there was two 250gb Seagate drives inside,i guess i don’t mind but i was surprised.
It has a power switch unlike some others, which is good.
Here is a link. http://www.amazon.com/Maxtor-F01H500-OneTouch-500GB-External/dp/B000EDNYSI
go and buy seagate hard drive. Its best external hard drive manufacturer.
I have a Western Digital 400 GB external USB hard drive (My Book). I think that it is great. It spins at the speed of 7200 RPM and is real easy to install. All you do is plug the AC adapter into the wall and plug the USB plug into a USB hub and it will install the drivers it needs for you. It is like having a giant flash key. I totally recommended this. Good luck with your decision!
Lostinspace
I have a nice little Western Digital external hard drive. I don’t remember how big it is but it’s less than 100 Gb. Anyway it serves my purposes and works fine.
If you are buying it online I would recommend newegg.com. They have reviews and famous service (although I haven’t actually bought anything from them yet). If you already have a place in mind go with that but you should at least read reviews on newegg.
That’s my opinion anyway.
look in your case, you might have a port open for another internal drive.
If you have a newer system you probably have a SATA controller. This will be much faster than an external drive, and a hell of a lot cheaper.
2 screws, and 2 cables, and you will be all set 
only time I recommend an external drive is if you need to take it with you somewhere to use on another computer.
If going Fixed, think accessibility
If going portable, think low power
I just bopught a NAS (Network Attached Storage) drive at 1 TB.
It works like a computer on your network/server which stays on constantly and can be accessed by multiple computer. Great for a home network, and can also be accessed via the Internet, so great for needing to access files while I am at work for example (no more sending it via Email.
My other portable HDD is a laptop drive which has very low power consumption so works off USB. No need to plug in an annoying external power pack like you need to with 3.5" enclosures. works on a single computer, but can be dragged around with me anywhere.
Alltaken
Well, I bought an external HD 6 months ago, loaded a whole lot of stuff onto it, and next morning it had a head crash which gouged large grooves into the platter… bye bye bye…
NEVER TRUST A HARD DRIVE
All hard drives are pretty good these days.
I used to use a 6GB one that i had from my first PC without any problems for several years.
Go based on the spec. If you just want mass storage go on size (rather than spec/ speed)
It just doesn’t matter much. Get a good deal.
Buy two!
Back it up…