matrox parhelia dvi problems connecting beamer and lcd

hello

i want to connect my new beamer panasonic 700 ae to the second dvi port
on my parhelia.
on the first port my lcd works really fine in 1600x1200. when i connect
the beamer both devices can only show 1024x768!
up to now i tought that the parhelia is dual head and i can use 2
independent resolutions... but this is with dvi not supported.... :-((
then i switched my lcd to vga as second display on the card and my
beamer becomes first. but then only 640x480 was possible on the beamer.

are there any ways to get 1600x1200 and 1280x720 work on both display
devices in the same time??
do i need another driver or software tweak? or do i need another vga
adapter like a ati radeon 9800???

yours
christoph