hi stu. if you are new then i guess your brain is the best software for starters! read in the strategy section and learn as much as you can! you might even like to start the NL beginners course as well - this will get you going and give you a solid grounding in the basics and it will also introduce you to software and stats..
as far as software goes, i use holdem manager 2, although people have mixed feelings about it. you should check out holdem manager 2 as well as pokertracker. both offer free trial period (i think it's either 30 or 60 days) and you can make up your mind which one you prefer. at the end of the day, both do the same thing.
there is also the pokerstrategy.com elephant which is free, but i can't seem to find a link for it. i'm sure a mod will come along and let you know about that