I've got a Celeron 400 on an ASUS P3B-F mobo (jumper-free rules!!) and before I get myself into trouble, I need to know how the voltage setting works with the multiplier and frequency settings.

I gather that with a Celeron 400 the multiplier is locked so I have to leave that alone and try messing with bus speed - TRUE? If I do how will that affect other hardware?
Hardware installed:
Celeron 400
ASUS P3B-F mobo
128MB PC-100 RAM
3dfx Voodoo3 2000 PCI 16MB
Diamond Monster MX300 Sound
Western Digital UDMA/33 10.1 Gig HDD
Acer 50x CD-ROM
Some off-brand 2x2x6 CD-RW

Also, how does the voltage work into all of this?

Any cooling suggestions?

Any help will be greatly appreciated.