Steve,
I guess you can find every description you want about those arts just on the internet or visiting the next bookshop.
As a matter of facts, you are the only one who can decide, so go see these classes (even more than once) and talk to the teachers.
My suggestion is: decide what you want first (competion, fitness, self defence, meditation etc), go talk later.
Rgds,
the european
Seconded.
Steven To,
(for some reason I can't reply to your post in the thread it was moved to)
If you are rather small Jui Jitsu is probably best for you. However- check out each of the schools near you and decide which fits you better.
You can always switch later- or take'em all if you can afford it.