Note: I do not work for Intel (well, I did, but I am retired now), so don't shoot the messenger!
Intel has no plans to provide support for Windows 10 on any of the Intel Desktop Board products. As I understand it, Intel's commitment is to provide fixes for serious BIOS issues (like security flaws); they will not provide any new features or feature improvements (and support for a new O/S *is* a new feature). All of the Desktop Board products were End-Of-Lifed some time ago; there are no longer any resources available that could do the development or (especially) the validation that would be necessary to formally support a new O/S.
Ok, that said, all is not lost. Intel has committed to supporting Windows 10 for specific past generations of its component products and this encompasses the drivers for the processors, chipsets and other (Intel) components that are present on the 7-Series and 8-Series Desktop Boards and the 3rd and 4th generation processors that these boards support. Because there are no resources available to do so, however, Intel will not validate these updates on the Intel Desktop Board products and thus you will not see them made available via the download pages for these boards. There are alternate locations that you can use to get these drivers. They should work on these boards but there are no guarantees; you are on your own to try them. Here are some links to help you:
Select and Download Latest Intel Graphics Drivers (select the appropriate one for your processor)
Download Latest Realtek High Definition Audio Codec Driver (this link is to Realtek's site)
Next, let's talk about IDU. You are absolutely right; after upgrading from Windows 7 to Windows 8/8.1 or from Windows 7/8/8.1 to Windows 10, you will have to reinstall IDU. Why? Because Microsoft, in all their wisdom (I am being nice), deletes all or part of the application (including supporting DLLs and Drivers) as part of their upgrade process. Why? I can't answer (I said I am being nice and can't do both).
Oops, I realized I provided a link for the latest WLAN software; here's the one for the latest LAN software:
Added this link to response above so all links in one place...
Thanks N.Scott.Pearson for the information you have kindly provided here.
Stany what N.Scott.Pearson has mentioned is true; unfortunately Intel will not make new software or drivers to support new operating system.
I really apologize for any inconvenience and thank you for the time you have taken to post here.