does your monitor work when you are outside of X? i had a similar problem before. it was solved to setting display type to 'both' in bios (i.e. using both integrated lcd and the vga port at the same time). when i had auto (the default setting) i had to have the monitor connected during the notebook startup to have some output on it...How can I use the external monitor? (it seems that the standard X configuration is not good). It is only a configuration problem, or there is something to do in order to enable the secondary monitor?
your terms in bios might be different (as i have different notebook), but maybe you should check this...
regards, -- Lubos _@_"