If u use Win 95/99/2000 then leave this enabled. If u run Linux or NT on that system then turn it off.

AFAIK this BIOS setting only affects whether the BIOS lets the OS reconfigure the resources (mainly IRQs), or configures them itself.
 
Usually, you should leave it on if you're running a PnP OS (like the setting says) like Win98 or Win2000.
 
The reason you might have needed to turn it off could be that it's an ISA network card, right? And by any chance an ISA "Plug&Play" card (not all ISA cards are PNP!)?
 
These ISA PnP cards are EVIL! THEY MUST BE DESTROYED!!!!.......... Uhm, sorry for that.. But you need to DISABLE the card's PnP feature (there's often a jumper on the card for that purpose).
 
And then you need to manually configure the card's resources under Win98/Win2k, as it won't detect them anymore without the card working in PnP mode.
 
As always, you get a stupid (i.e. inpracticable) tip from me: get rid of any ISA cards in your system. That makes your system run even better, and often gives you additional power management features (like enabling the hibernate feature of Win98(!) or Win2k if you used uncertified drivers for the ISA cards before).
 
nova.

Actually it was a new PnP PCI 10/100 Mbit card
 
But anyway, what DO I actually gain by letting the OS decide IRQs and such, as opposed to letting BIOS do it?

what you gain?
if you set it off, you wont be able to change the resources configuration in your pnp os succh as windows !

I dont think Windows 2000 seems to even care about this setting, it sticks ALL my expansion cards on IRQ 9 (isnt that the re-direct of 3?). I manually set them all in BIOS so there are no conflicts on my system but Windows just sticks them all back on 9 and I cant change that in Windows 2000. I have no problems as far as I can tell but has anyone else had this problem and found a solution? Check your resources, whats all your stuff on?
 
eraser-

Windows 2000 doesn't give a fiddler's fart if your PnP option is on or off. The problem is the ACPI setting. If you use Windows with ACPI turned on, it stacks all your hardware to a same IRQ (IRQ11 in my case) and this could cause problems if your hardware don't like each other. I could only use my Motorola SM56 PCI modem if it was occupying an IRQ by itself. For this I had to turn the ACPI mode off. Microsoft actually recommends to turn the PnP off so I have it turned off and Win2k doesn't care. It functions as a PnP system no matter what. So go ahead and try turning the ACPI off. And if you still have stuff on the same IRQ try changing your hardware to different slots. You can find info how to change from ACPI to NON-ACPI here:
http://easyweb.easynet.co.uk/~stevemcd/win2000.htm
 
The only difference I noticed is that I need to actually press the power switch when I shutdown the comp. And ACPI turned off you can use APM if you want to use power management. Tell me how it went.

Topa is wrong, you must turn off PnP in the bios. If you dont you are subject to errors Like config_intialization_error or just a blue screen telling you about the error and to reboot. Let the bios and the motherboard sort through all the cards and then let it pawn off whatever is left to the OS. Turn off all bios shadowing as well. Reset your configuration data for kicks.