Upgrading Nvidia onboard to ATI-9600 problems

Hi I am a newbie at upgrading computers and am having problems installing my ATI All-In-Wonder 9600 video card.

I have a HP 2600+AMD Athlon XP processor with an integrated NVidia GeForce 4MX GPU running WinXP service pack 2.

I uninstalled all my nvidia drivers and plugged in my ATI card but all I get is a black screen when I power up. The instructions say that I should be able to access my bios to disable the onboard card when i restart but i can't see anything.
If I uninstall my nvidia drivers won't that also uninstall the GART drivers which I need for an AGP card?

Any help would be much appreciated. Thank You

With the ATi card installed, plug the monitor into both the onboard card and the ATi one and see which is being initialised. If you uninstall the drivers it won't cause any problems and you need to do this anyway. If you are getting a blank screen on power up it's not a Windows related thing. Make sure the AGP card is fitted fully and properly and check your motherboard manual to see if you need to switch a jumper or DIP switch away from onboard to external AGP card.

use drivercleaner to remove all trace of nvidia drivers from windows install.

remove the ATi card, boot system, hopefully can get into BIOS to disable the onboard. shut down and install ATi card.

should be golden.

What's probably happening is the nVidia integrated graphics are still set as default in the bios, check if you get a screen when plugged in to the nVidia. If you do then go in to the bios. First you will want to change the "primary display adaptor" to AGP. In the main menue there should be something like integrated features or onboard features, something along those lines. Go in to it, there'll probably be something with NVxxx or something with the word nvidia where it says integrated display or graphics. You will want to disable this.

When you save and restart the display should come through the ATi card.