Could someone please tell me how to remove an incorrectly installed video card driver and replace it with the standard vesa driver using the command line, im using RH9.

That depends upon how it was installed.

Red Hat 9.0 Package Management Tool

# Guides to software management
LNAG - How do I install a program I downloaded from the Internet?
Rute Guide's software explanation
You might want to check out CheckInstall to manage source code installations/uninstallation

# Red Hat links
Red Hat Linux Manuals
Get your mp3 support here
Maximum RPM
rpmfind
Easier software management: apt4rpm - Red Carpet
Red Hat 8.0 Tips & Tricks

# Red Hat 7.3 down configuration commands
setup leads to several configuration tools

# Red Hat 7.3 up configuration commands
Configure soundcard:
redhat-config-soundcard
Configure X server:
redhat-config-xfree86
Configure network:
redhat-config-network
Manage software:
redhat-config-packages
Red Hat 9.0 Package Management Tool
Manage users
redhat-config-users

# Handling NTFS
New Technology FileSystem (NTFS) HOWTOs
Linux NTFS project

It was installed using one of the options included with the OS.
The system will boot as far as a command prompt where I receive a message about the incorrect driver being installed then back to a command prompt.

Remember, all we know is exactly what you post. Posting exact error messages are good. Telling exactly what you typed/clicked/etc is good. We have no idea of what you installed and how as the question stands.

How to get good answers with your questions about Linux

Undo the editing you did for your /etc/X11/XF86Config-4 file.

# Configuring X
Linux Hardware Compatibility HOWTO - video cards
The Linux XFree86 HOWTO
Configuring XFree86 for a Non-Specific Linux Distribution
Common X configuring tools:
Debian - dpkg-reconfigure xserver-xfree86
Mandrake - XFdrake
Redhat 7.3 down - the setup utility leads to several config tools
Redhat 7.3 up - redhat-config-xfree86
You may have these tools:
XF86Setup
XFree86 -configure
Xconfigurator
xf86cfg
xf86config
xconf
ATI Linux drivers
If you need the nVidia driver, you want the Linux IA32 driver