R help - Nov 2005 - generalised linear mixed effect model, glmmPQL

Dear listers,

I am trying to get more familiar with concepts underlying generalised 
linear mixed models, mainly through Venables and Ripley (fourth edition) 
and the R-list archive. Of course, as a  possibly tool-user biologist I 
am not that easy with every d??tails of the mathematical aspects of the 
optimisation methods described. I am trying to sort out which could be 
an acceptable strategy for model comparisons and selection. I have 
understood from the R-list archive that AIC and similar approaches are 
not valid for model comparisons with PQL. On the other hand, table 10.4 
in Venables and Ripley compares the results of various fitting methods 
(thus the fitting methods), but my wonder is about  comparing  models 
(or parameter estimates) given a  method.

Can somebody put me on the track with some hints or  basic references 
for "dummies" if any...

Thanks in advance,

Patrick