After we began digitizing our home movies, it became apparent that our 100GB hard drive was not going to cut it. We also have a large music and photo collection, so I decided to start looking into options for backing them up.
There were some factors that we considered when picking out a hard drive:
1. We wanted an external drive. With two laptops (one being a Mac), the cost of 2 larger internal drives wasn't worth it.
2. We needed a backup drive that was both PC and Mac compatible.
3. We wanted something affordable, but did not want to purchase a hard drive from a manufacturer we had never heard of.
The Western Digital 500GB MyBook Essential Hard Drive fit the bill. We got it on sale last fall at Best Buy for $120, but I have seen it recently for about $90 after a $40 mail-in-rebate.
I would highly recommend this hard drive to anyone looking for a good backup hard drive. It has a USB 2.0 port, so you just plug it in and you are ready to go. I have had no problems switching between the PC and the Mac. It has been really reliable - no complaints!
I keep this hard drive in the same spot at home, but in my opinion it is not extremely portable. It is larger than the portables I have seen, and just is not designed for on-the-go use.
My only warning would be that it has just a USB 2.0 port (no FireWire or eSATA), so transfers are not that fast. This is fine for our use as a backup drive, but if you are looking for something more similar to a second hard drive, Western Digital also makes a MyHome edition (which has both FireWire and eSATA compatiblity).