I believe that Teamspeak is a must, i believe our Guild would benefit from it and will become better in Instance's and Raid's, it is alot easier than typing.
you need a headset with mic from £10 upwards.
You don't need a mic you can just listen in using your pc speakers, Its quicker to talk than type.
Also at times we are not raiding, teamspeak seems to get the guild talking together this adds a bit social aspect to the game and at the end of the day it is a game and its all about having FUN!!
I Hope You enjoy it,
Nostromo.