the cent dvd dose have gcc on it
that is why
"CentOS-6.0-x86_64-bin-DVD1.iso" is 3.9 gig's
CentOS-6.0-x86_64-bin-DVD2.iso is 1.1 Gig's
or is this the tinny live cd that is 689 Meg
if the live cd
there is basically nothing on it .
I am unable to connect to internet through command line so can't use yum command although I am able to connect through firefox.
that normally means you are behind a router
set up the proxy as described a few posts above .
you might also want to READ the Cent wiki
however you are using "virtual box" on a Windows 7 install
you might want to ask the VB people how to configure it on Windows7