This comes from the Dell Forum. A good place to get answers. Never tried the solution but the problem has come up before on the forum. You don't need to do the first part of the solution, but it may be helpful
You will need to install a PCI video card, and disable the integrated video. Your PC does not have an AGP slot as you learned. Shop around and search: PCI Cards in the Forum Search for suggestions, there are lots of them (suggestions I mean)
2350 A02 -
* Click here to set your Dell home page
* Register using your e-mail address and system service tag (if asked)
* If listed, click Home and Home Office
* Under "Alternative Sign In", type in your Service Tag number [press Enter]
* Close the smaller popup box if it appears
* On the left, click Documentation
* Click Adding Parts or Tech Notes, look for "opening the computer cover" or "Removing and Replacing Parts"
* Power down and open the case
* Insert the new video card in a PCI slot, BUT leave the monitor attached to the onboard video card!!
* Turn on (or restart) your computer
* When the blue DELL logo appears, press F2 immediately
* Arrow over to the Advanced tab
* Down arrow to Peripheral Configuration [press Enter]
* Down arrow to Primary Video controller, change this to AUTO or PCI (whatever is listed)
* Press Escape to save your changes and exit the system setup. BUT leave the monitor attached to the onboard video card
* You should now be going into Windows, go ahead and load the drivers for the added video card. When finished, don't let the system restart
* Press the Windows + Pause/Break keys
* Click the Hardware tab and/or the Device Manager button
* Open Display Adapters
* Double click the Intel listing
* Click the down arrow by "Use this device" and change it to "Do NOT use this device"
* Click OK and close all boxes
* Click Start- Shutdown- Shutdown- Ok or Click Start- Turn Off Computer- Turn Off
* Connect the monitor to the added video card and power the system on
Good Luck and please let us know if this works.