Can't you disable USB in the BIOS ?

Loading a useless driver will still cause the device to want resources if it is not disabled. Have you tried disabling in device manger ? It could free up some windows resources but if the bios is assigning IRQ's then you need to disable it from the bios to make it totally disappear.

You can simply set the device to "not used in this hardware profile".

But apart from that, a device with no driver DOES NOT use resources. Windows even tell you that in the device properties.

I respectfully disagree. If you have a LPT port or Com port that the motherboard or addon card physically assigns an IRQ then it will use that resource even if Windows says it does not. I have this special diag card that has proven this to me many times because it checks at the true hardware level and not thru software.

Why not just install Win95 rev C (OEMSR 2.5) with USB support and updates?

* Can you disable it in the BIOS?
No. Surprisingly many of my boards have no options for disabling various integrated peripherals. I'm continually amazed. (Also very few allow you to disable option ROMs. I thought I used to see that feature everywhere, and now I wait for 2940s to initialize way more than I care to.)

* Can you use OSR2?
I could, but I've gone on this pointless mission to run Win95A on my Pentium 166 MMX, and Win95C on my Cyrix 6x86 PR200+ because I want all of my builds to be on unique OSes -- partly as a self-imposed restriction that prevents me from hoarding collecting ALL the computers. Both boards have on-board USB, although perhaps the Cyrix's board has a BIOS option to disable it, and so I could maybe switch them. That said, I am really feeling 95A's age. 2GB partition limit, no USB at all, no DMA for disk access... This was really the turf of late 486 and early Pentium systems. Can't believe I ran a PII-350 on 95 for years.

* Can you just disable it in Device Manager?
Yes, but the hardware still has its IRQ allocated. My guess is that PCI IRQ sharing will only work if the drivers can coordinate it, since I am unable to allocate its IRQ to anything else without getting a conflict warning. (Maybe it can't be shared at all for some other reason though.) For now, I've allowed it to conflict with the tertiary IDE channel on the AWE32, and I've disabled both in DM. Sloppy, but I guess it works.