[R] compute probabilities on a Bayesian Network

[Marcio Pupin Mello]

Deal R Users,
I'm trying to find out how can I compute probabilities on a Bayesian 
Network using R. The Bayesian Network I modelled is shown at 
http://www.dsr.inpe.br/~mello/1727/BNgrapmodel.png and I'd like to know 
how can I proceed (commands on R) to answer questions like: (1) what is 
the probability of S=T given C=T, L=T, R=F, H=F and D=F; or (2) what is 
the probability of S=T given C=F, L=F, R=T, H=T, and D=T; or even (3) 
what is the probability of S=T when my only one evidence is that C=T 
(i.e I don't know the other variables values). I used Microsoft Belief 
Networks to compute the results but I don't know how to do it with R.
Looking forward to receiving replies!
Thanks in advance,

Marcio Pupin Mello