HRM vs Activity Monitor?

Hi All,

I live in the UK and want to get either a good HRM or Activity Monitor and at a bit of a loss as to which is best.
Want something which will track calories burned, heart rate, sleep etc.

I do martial arts training twice weekly and would also like to check calories burned there etc. so I'm thinking more toward a activity monitor but just not sure.

I know I can work most of it out but I'm crap at math (dyslexic) and love my gadgets.

Anyone advise whats best? I have family in Oz and could use them to get my hand on a BodyMedia Fit Armband but will it do what I need and is there better out there?

Any Advice appreciated, would like an explanation/experience info rather than just get this one....

Cheers

Jim