Depending on how old you current computer is you may or may not have to upgrade you computer. If it is under a year old then you may be able to upgrade and use most of the hardware currently available. If you PC is older then if you replace you motherboard then you might have to replace most of the other hardware as well.
The motherboard would not directly change the speed of you computer, but it will allow you to build upon it and use the latest equipment if upgraded.
A solt-370 (celeron type M/B) for use with celerons.
Use a Aopen, ABit, Soyo or Intel. There are others but I cannot
name them all.
A Slot-1 (Pentium III), dual M/B with onboard SCSI controller
Soyo brand M/Bs are excellent for this purpose