The easiest way is to back up the drivers before you format your hard drive. There are several tools to handle this. One such free tool is Driver Backup that will allow you to backup and restore your drivers. You can use this tool to export drivers from either Vista or XP.
Download the tool (330Kb) from here and unzip it. Run the tool (Windows XP required .NET Frame work2) and it will lists all drivers from your computer. To back up, click on ‘Start Backup’ button and select a path to back up. You can restore this using ‘Restore’ button.
One of the important things about this tool is that, it will allows you to pick a particular driver that is installed on the system and export it into a folder for reinstallation later.