Monitor driver missing

I had to do a new reinstallation of Windows XP and in the process seem to have lost all my drivers.

My E151FP monitor is only showing 640x480 pixels and I cant reset it

I have a Dimension 2300 with a 15" LCD flat panel - not sure what video card, but it would be

standard Dell issue - purchased in late 2002/ early 2003

I have downloaded the driver and am trying to get my driver installed but having problems at step 3 below

 

1. Click Start-> Control Panel-> and then double-click
  Display icon.
2. In the Display Properties window, click the Settings tab, and then
  click Advanced.
3. Click the Monitor tab, and then click Properties -> Driver tab ->
  Update Driver.
4. When the Hardware Update Wizard dialog box appears, choose
  “Install from a list or specific location" and then click NEXT.
5. Check the "Include this location in the search" box.
6. Type the path to the location where the driver
  files were extracted (most likely C:\Dell\Drivers\E151FP) or use
  the browse button to select the location.
7. Click Next -> Finish to complete the installation.

When I'm at Step3,

The Properties button on the Monitor tab is greyed out and I cant click on it.

The Monitor type is showing default monitor.

 

Can someone help

Thanks