My wife recently replaced her ThinkPad T40 with a MacBook Pro. To save me time in the future, when a crash or data loss occurs, I decided to use Apple's built-in Time Machine app for the Mac and get the Mac system recovery app SuperDuper set up on a Western Digital Passport USB drive. The problem with this setup was that it relied on her plugging the USB drive into the MacBook Pro on a regular schedule. The solution was to set up NAS on our home network.
I quickly settled on two options: Apple's 1TB Time Capsule (which combines a router and a hard drive) or a combination of a Western Digital MyBook World Edition (MBWE) and Linksys Gigabit N router. In terms of backup, storage, and network connectivity, the MBWE plus Linksys router provided equivalent functionality to Time Capsule.
What to do?
Time Capsule was $30 cheaper than the MBWE plus Linksys router option. However, since MBWE is running a Linux kernel, the ability to add functionality to the device was almost limitless. There's a strong community of MBWE users that have everything from BitTorrent clients to PHP to a PBX running on MBWE devices. Even out of the box, the MBWE provided more functionality than Time Capsule, such as a Media Server. These "extra" features that the MBWE provides out of the box versus Time Capsule were not ones I'd originally considered part of the purchase decision. But when I learned about them, I tried to figure out if I could add these to capabilities to Time Capsule. While Time Capsule runs a stripped-down FreeBSD, it seems that the code is loaded onto a chip and not modifiable.
While both Time Capsule and MBWE are built from an open source kernel, the user freedom afforded by the two products is vastly different. Time Capsule is not meant to be tinkered with; MBWE is arguably not meant to be tinkered with either, but Western Digital knows that its customers are doing so and is making it easier to get more out of the device than the functions with which the device ships. For instance, the old version of MBWE did not support SSH access to the device out of the box. But since that was the first thing that MBWE users built a hack for, Western Digital smartly responded by adding this function in the new version.