So... These days graphic drivers are probably too much complex to be modified by users.. Though once, some people used to fix and improve them, without having to wait for ATi or Nvidia grace
I could find some names in this comparison. Omega, DNA, NGO, DHzer0point...
They may be worth a look for anybody on older cards with special needs. In particular AGP compatibility issues should be solved.
Please take note not every driver supports Windows Vista.
Original hosters are down or discontinued by now, though mirrors are available
Thankfully Intel graphics is still so slow and buggy that compilations are a must.
Putting aside the famous intellimodder (old mirrors, caution it screws with power plans), you have:
For anything from Ivy Bridge and above instead (dx11 igps), really, don't bother. Some slight overclocking or setting Windows to high performance energy profile is the most optimization you can reasonably get.
EDIT: in fact, I think I just now figured out the functioning basis of all the hacks that have ever been. Intel older igps were so shitty, that despite them having in-hardware support for some features (such as SM3.0 and T&L), you could actually get them offloaded to the cpu and increase your performance. Because whatever the obvious overhead this operation has, it was still faster than tasking the potato gpu with yet another operation (or maybe vertex processing is just straightaway quicker on a 200€ cpu of the time, compared to a 2€ graphics adapter).
Anyway, for these reasons the driver has a registry whitelist codenamed "Enable3DContexts" (I don't even want to think instead to that can of software worms Gen3 was). In my testing with a X4500 and the latest 2869 stock drivers, I found out that after setting Mass Effect exe to 1, frametimes improved by more than 10% (benchmarks and a bunch of newer applications seemed to have the mysterious value of 2 OOTB, mileage may vary on what's the best one).
Once accounted for that, there was no other difference in ME1 and HL2 across all the 4 modded drivers. DODSQE maybe is the only other thing with a possible 3D speed impact, but I couldn't confirm.
So.. I believe that a fair TL;DR would be that at least if you are on a desktop, in the proper Windows version the official drivers were released for, there's no need to install anything else. Even though in 2020 it's probably easier to find and download a hacky community driver, than the actually latest version from the intel website.
I guess W10 (though there is the question of why even using that when you are low-end-gaming hard) or laptops are different story instead. The original .infs might even have been explicitly disallowing "forward-compatibility", and for example Display1_EnableDynamicScaling is allegedly among the requirements for metro (thus UWP?) applications to work properly.
Let alone laptops, whose silicon may even be identical, except that they have been heavily down binned. And then there's all the LVDS voltages and timings, or that god forbid OEMs let you had a nice BIOS with all the right memory settings.