Where to find driver ?

Based on the 9.3.0.1019 version you're showing there, you already have installed the Intel Chipset software. You've rebooted since, right?  Not every single device in that section of Device Manager is updated--most aren't, in fact. If you want to make doubly sure, just extract the Chipset software to a temporary directory somewhere (use something like 7-Zip to do that), and then right-click "Intel 4 Series Chipset PCI Express Root Port - 2E21" in Device Manager to attempt to update the driver manually. Point the dialog to the "All" directory where you extracted the Chipset software. Most likely, it'll simply come back and say that the most appropriate version is already installed.

I'm using a Series 4 motherboard with Win 7 SP1 (32 bit) as well and I notice your point Soda. Even though I've tried the latest Inf package specified for my specific board (DG45ID) also the latest version for the Series 4 Chipset, it still leaves lots of Microsoft drivers in place even though they're all dated from 2006 (older than the inf package dates)..

Although Winzip 14.5 wouldn't extract the inf package contents for me (it just wanted to run the exe files) it is possible to extract the package contents into C:\Program Files\Intel\InfInst by running the exe with the -a switch. To do this put your downloaded inf package file in a simple location on your HDD. I put mine in a folder I created C:\Temp. If you then click the Win 7 Start button and type run into the search programs and files box and press the return key, you'll have the run box ready to go. In my case I typed in c:\temp\INF_allOS_9.1.2.1008_PV.exe -a and the extraction (only) completed successfully.

On examination of the infs under the extracted Win7 subforder, I notice there's only a few infs that a relevant to my board and these are actually installed. I suspect that's the way its meant to be as my boards working fine as is. It is disconcerting on running the installation and seeing a huge bunch of files being extracted, to find only a handfull are used though.