> is it possible to prepare for a certified (big North American Linux
> vendor) engineer exam with a CentOS install ?
I assume the Linux vendor you mean is Red Hat, then yes, you can.
> I have heard that the test contains questions on specific GUIs, are
> they included in the CentOS distribution?
I am an RHCA and I did all my preparations for exams with CentOS (except
for the RH423, it uses Red Hat Directory server).
CentOS and Red Hat are more than alike enough for the exams (and the
courses by the way
CentOS mailing list