Vista - Inspiron 700m external monitor fails to work as primary on Vista

I will be very happy to send some gift from Spain such as wine, some fine
food etc to whoever will help me to solve this problem. So please read
carefully.

I have Inspiron 700m, BIOS 7, winth both Windows XP Professional and Windows
Vista Enterprise on it. I connect it to Philips 180P2 LCD monitor , whcih has
two inputs - either direct VGA cable or DVI and DVI to VGA cable.

Under Vista, I can mark external monitor as "Attached" and then it displays
the external desktop. When I mark it as Primary, it suddenly forgets that the
monitor was attached, and I am back on laptop LCD without external monitor
activated.
The Fn+F8 does not work at all.

Under Windows XP it works fine as extended monitor and as primary monitor.

I tried to install third party application for switching monitors - Ultra
Monitor or something like that, but the effect was the same.

I think the monitor detection does not work correctly on the 700m under
Vista - is there any trick to enable it again? Or hard code that this monitor
is attached and ok?

I hope it is not mainboard fault - it is also strange, that XP is ok...