cannot display this video mode optimum resolution 1280x1024

Hi,

I have a Dell Dimension E520. I tried to install a Nidea 7300 series graphic's card on my PC but when I try to re-boot i get this message "cannot display this video mode, optimum resolution 1280x1024 60hz" appears on my Monitor. I can't access my desktop to change the setting for this, any idea's how to fix this?

Thanks