This solution does not work yet, due to lack of driver support. As soon as dual graphics solutions (e.g. NVIDIA’s SLI) become available, a simple multi-display dream can easily come true.
One question that came to mind quickly : now that we have two graphics interfaces, what stops us from inserting two graphics boards at once ? We first tried two GeForce 6800 GT cards, the first inserted into the x16 PCI Express, and the second placed into the AGP Express slot. Though the system started Windows, it crashed after only a minute. Since we used an ample Antec 550 W power supply, we have to blame the motherboard for not delivering sufficient power. Next, we tried an older GeForce4 Ti4200 card. Voilà, it worked properly.
Unfortunately, there is no way to benefit from the additional graphics capabilities yet. As soon as NVIDIA introduces their SLI (Scan Line Interleave) technology, the Detonator drivers will be capable of managing up to four displays. We hope this will work with different NVIDIA VGA cards and without the SLI link.
We would like to underscore that this method of having multiple displays (using an older AGP card and a new PCI Express model) is unsuitable for demanding 3D applications. However, expanding the desktop to three or four monitors might be helpful in increasing "desktop real estate" for the many users that have to cope with lots of windows and tool bars every day.
Another problem with this setup could arise due to the nature of AGP Express, which as we have said already is not a real AGP slot. It is very difficult to know whether all AGP graphics cards will actually work in the motherboard. We did not find problems while testing, but of course we used only a fraction of the AGP cards out there.