I would stay away from western digitals nas drives if you plan to backup to it a lot. I work for a pc/Mac repair shop and we went through 3 of them before settling for a nice raid setup in a server instead, none of them made it longer than 30 days.
Time capsules from apple are nice, will easily work for the Mac no problems, and should last you. Another option is get carbonite or mobee and save your stuff online so you never have to worry about the nas falling over or dropping, even off it will kill the drive. Not to mention a lightning strike frying it and/or the nic right out of it.