Hi guys i have 2 gigabyte motherboards i just want to integrate both of them for the purpose of speed. First of will i be getting more speed if i do? If so tell me how? If not what will be the advantages and disadvantages.
Looking forward for ur kind replies. If answered i'll be happy and thankful.

Not sure what you are wanting to do. If you mean to use them in parallel so both computers (which is what a populated motherboard is) can both crunch on the same task then that is possible in theory but not practical for home use. Note you would need something to control both of those computers too. Distributed computing projects, such as Folding @ Home, use mainframes to control the individual computer assignments.

One computer has pentium4 and other has celeron microprocessors. One has 2 512mb RAM's and other has 2 1GB RAM's. I need to combine both to have best performance. Still not clear sir?

I have 2 160HDD and a single system don't get to desktop with 2 of them don't know y.

Still not clear sir?

Not really. Are you trying to make one computer using parts from both to make the best combination? Or are you trying to have both computers working together on the same task so together they can get done faster?

You might be able to combine parts to make one computer - but we would need specifics first, such as model motherboards, exact models of CPUs, RAM, PSU sizes, and graphics solutions.

To have both computers running at once on the same task it is pretty complex and would require a fancy controller with software to control it.

May be both of the questions are wright? Tell me which is the best

Sorry have to go see u tomorrow

Using the best parts from two to make one. BUT, they have to be compatible.

Ok sir these are the specifications of my computers.

CPU 1: motherboard:gigabyte:8I845GVM-RZ
up socket: 478
up: celeron 2.40GHZ
RAM: DDR400 DIMM package

CPU 2: motherboard:gigabyte:CA-8I845GV
up socket:478
up: pentium4 2.40GHZ
RAM: DDR400 DIMM package
According to my knowledge these are information's i could gather. If any more wanted please tell me and teach me how to get it.

First, let's make sure we use the proper terminology. The "CPU" is the central processor unit. The main computer "chip" or IC mounted on the motherboard. In this case, the Celeron and Pentium 4 are your two CPUs and together with the motherboard, RAM, case, etc. make up your computer. It is a common mistake to call the big box a "CPU".

Those are almost identical motherboards. You mentioned your RAM type but not how much. Your board supports 2 sticks, up to 1Gb in each slot for a maximum of 2Gb. It looks like the only thing you might be able to do is combine the RAM. BUT, you need to determine what is there first. If all the sticks are the same size, and both slots are already taken, then there is nothing you can do.

To increase performance, you only option may be to buy an add-in graphics card. You motherboards only support PCI (not the same as PCIe) so that limits your options, but there are still some decent PCI cards around. HOWEVER, graphics cards are power hungry so you MUST ensure your power supply can support the added load.