If your Bios VGA IRQ setting is enabled, you should leave it that way.
Although, for booting and troubleshooting, you could Disable it. It (usually) just won't work with anything 3D that way, but
should work fine in 2D.
Choosing another PCI Slot commonly helps.
It's just important to try and get the Video Card its own IRQ.
And since we're talking Resources, you should disable all unused Onboard devices (e.g. COM ports, LPT Port, USB, Raid Controller, Sound) if you don't need them.
Every single one can free up an IRQ for you

(Win9x Drivers often have problems having to share Resources among different Devices, so keeping the system resource-friendly by deactivating unused Devices is a good thing to start with)
And of course, I assume you have the latest Chipset Drivers installed for your Motherboard ?
(intel based Systems usually don't need anything, but on SiS, VIA, ALi or NForce based Boards, those Drivers are really needed)
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Worst case, you either have to wait to let it boot once, or enter the Safe mode and manually Deactivate potentially conflicting (or unused) Devices from there in the Device Manager. (that way, they can be re-activated easily the same way, both in Normal or Safe Mode)
Finding out what IRQ's are shared among what devices is the most important thing.
If completely unable to look at it under Windows, the initial Boot screen (after the Motherboard counts up its RAM and detects the HardDrives/CD/DVD's), it should show up for a second.
Press the "PAUSE/Break" Key to halt the text output.
(it's a bit tricky, but by quickly pressing any key to resume, and almost instantly the Pause Key again, you can slowly progress and catch the right moment to halt the machine at the right spot

)
PS.
The Video Card's Driver can be changed to "Standard VGA" (= vga.drv) in Safe Mode as well. That should do the trick.