Another important thing to note is that all the phones have a mini-switch built into them so you can run your computer and phone off the same line. However, one important thing many people seem to forget is that lots of them are only 100 Mbit slowing the desktop down as well.

Only certain models have gigabit like the Cisco SPA514G. Sort of defeats the point of getting a gigabit switch without the gigabit pass-through.

It's up to you whether or not you want to run multiple lines. A lot of law firms/offices we work with like the single line.