First, let me direct you to the
Scan.co.uk HDD page. That will give you a good indication of the current prices of HDDs. There are also SATA 6Gbps HDDs, but so far it seems that non-SDDs can't really make use of the extra speed.
Within that, Samsung Spinpoint have been the best HDD series since the F1 was released (at least without paying a lot more for minimal gains). This may sound obvious, but what makes the most difference in the speed and reliability of an external drive is always the actual HDD itself inside.
After that, if you must use an external drive, you can just look for the enclosure that you think looks best. There are so many out there with so many different build qualities that it's hard to recommend one. There are also lots of features to be aware of if you need to use it as anything more than a USB drive. I tried a number of enclosures with USB, FireWire, eSATA, RAID, built in memory card readers, even one which is simply a HDD dock (you stick in a HDD in the top, turn it on, use it, turn it off, take the HDD off and put another in - almost hotswappable).
Ultimately it comes down to what you need out of it. If you need something that's more portable than a desktop HDD, such as a laptop HDD, then you'll experience slightly slower speeds and much less reliability, but laptop HDDs can be powered from USB alone (sometimes they'll have a USB cable that plugs into 2 USB ports for extra power). They're much smaller and lighter, but that also means they're that much more vulnerable to movement and therefore die faster. I've used a 4GB and a 80GB laptop drive in my only 2.5" enclosure before, and the 4GB one is just not worth it (2 bad clusters that I can't seem to fix or work around) whilst the other became the drive for my oldest working laptop (still works well either way). It's useful, but I know from experience that they'll die faster if you regularly put it in your school/work bag. For reliability, capacity, and value for money, go with a desktop HDD. For portability and convenience, go with a laptop HDD if you really need to.
Now, answering the second question, the WD Elements drive.
- Looks... I don't like it. I prefer drives with a rounded top/bottom so it feels less like a brick.
- Size... I can fill up 1TB easily, but I have a lot of data that I occaisionally move from one external drive to another.
- Speed... it claims 60 (I assume MBps) although I take that with a pinch of salt because I know a lot of motherboards won't allow speeds that fast (although finding out which ones do is kinda tricky). There's always something wrong with either USB controllers or drivers that slows it down to 30-40MBps.
- Reliability... I've had one WD drive fail on me before, and 2 that still work. My neighbour has had 4 die on him over the years and currently has 1 still running (whilst the rest he uses are Samsung Spinpoint F1s). Some people say they're great, some people say otherwise. So long as it's not SeaGate, it's fine, although Samsung are better.
- Features... power efficiency means it'll spin-down after a 2/5/10 minutes of inactivity (depending on what it's set to). I believe WD offer some tools to change these settings on the drive. If you use the drive "on demand" a lot, you may want to disable it. If you only use it as a storage device (say, to backup your data, or store your videos to watch occaisionally), then it's a good idea to keep it. Better to have the choice than none, I suppose.
I wouldn't buy it for myself, but it can be less hassle than having to find a decent enclosure for a Samsung Spinpoint F4 EcoGreen 2TB drive (which is what I would pick myself, depending on how much money I had to spend on it).
