Newb camera help

[fred.r]

So I'm thinking of getting back into photography. Used to do some limited b&w film stuff a while back.
Anyways, thinking of going digital to get away from all the noxious fumes and what not of film. Problem is I'm clueless about digi cameras.
Plan on shooting a mix of portrait style stuff and "sports." (I ride downhill mountain bikes and we're kinda vain )
I would like the option of point and shoot while mainly being used manual. Camera will dual duty as a personal "family cam" as well as my nice camera.
Budget is between $200-$600 depending on quality vs. price of digital cameras, again I stress I have no idea about digital.
Just looking for some suggestions on what to look for, brands, models, features, etc...

[SmartWombat]

canonsx100: do you have any reasons why?

For MTB how about the Olymous 720 SW - the shock and waterproof one?
Our own Photo-John posted a review here