hey - thanks everyone!
redmer - yeah i made the base mesh in maya and then exported it over. i think you definitely need a tablet for zbrush - it just gives you more control and is easier to use. i've finally started to get into using one and it's a lot of fun.
GecT - thanks - it's never too early to try it out if you can.
gster - yeah - it's very cool - that last sentence sounds dangerous though.