I saw this: Detecting if a program is already installed with NSIS.
I want to ask the pretty much the same question for Inno Setup 5.
But basically my question is: Is there any way to check if a program (driver) is installed already on the computer so that i skip the install of the drivers from my [run] section?
Yes it is possible to check. How easy depends on what you want to check for.
If the driver package creates a certain registry key then you can use a
Check:parameter that callsRegKeyExistsor similar.The Upgrades article on the ISXKB wiki gives an example of how to check for entries added to the Add/Remove programs list.