lets get started. Does the mobo support dual channel memory?? Did you get two sticks of PC 3200 DDR 400 one 512 for each of the channels??? [there is some debate as to whether dual channel is significantly faster].
Forgot to discuss the Power Supply what size [wattage] do you have now?? What is the name of the MFR? If it is underpowered it should get you through the first steps and probably get the system working. If the system shuts down a lot or otherwise acts flaky you may want to get a higher wattage unit.
Carefully see if the mounting holes on the mobo match the holes on the existing mobo. These holes are the ones with the plated artwork circling the holes. They will probably match, except there might be one less on the new mobo so you must remove that extra standoff if so. BTW the fiber washers go under the head of the mounting screws simply for the purpose of preventing damage to the printed artwork around the hole as you tighten the screws. Yhey are not for insulation.
The idea is to mount the CPU, the HSF and the memory on the mobo before fitting it into the case.
The idea is to get into the BIOS ASAP, so just install the mobo with the CPU/HSF and Memory. Set for single channel or dual channel as appropriate if there are jumpers for that. Connect the power supply to the mobo, the power switch wires to the mobo and the other panel items including the speaker. No Keyboard no mouse. No cards or drives. Turn the power on and see if you get a lot of beeps [means that you have no video] That's a good sign [some mobo BIOS's don't use beeps. If power goes on, and CPU fan works great. Then add the video card [if it has onboard video you could use that and install the video card afterward]. If you have onboard video and plan to put an AGP card in you can first use the onboard to get into the BIOS and disable the onboard video and enable the look for AGP in the BIOS.
Note: observe all ESD precautions, ground yourself to the ccase metal as frequently as possible. Also, note that with ATX systems when you turn the system off by windows or at this time by the fromnt panel switch there is still 5 volt logic power on the mobo [many now have an LED on the mobo that lights from this voltage]. Best to remove that voltage whenever going into the case/mobo to add remove hardware. Either unplug the power supply or if the supply has an on/ off swich on the rear use that to turn it off. Better way because it leaves the ground wire to the house wiring still connected. [Don't forget to turn it back on each time.] I always forget and then feel foolish. LOL
Anyay, with the video and the monitor connected turn the system on, hopefully a single beep and you get the first screen on the monitor maybe a splash screen or gives video and BIOS info. If that works shut down and hook up the keyboard No use for a mouse yet. Turn on power and get into the BIOS and set the features that you want or need. Remember, other than USB ports, nothing else in a computer is hot switchable so ALWAYS turn the pwoer off for plugging or unplugging nything.
Get that far and then add one thing at a time and check that everything works. The next best is to install the floppy drive.
Probably insall a CD-ROM or burner or?? before the hard drive. You will want to install the motherboard drivers at the first opportunity.
Hopefully you will have all of the latest drivers for the other hardware and have backed up all key data.
From here you may have to ask for other advice in this thread. If you were putting in a new hard drive and then going to install the operating system it is simple. I'm not exactly sure what you will run into when putting in a drive that already has the XP operating system. My guess is that you will end up installing XP over itself [not saying reformat install, just over itself, hopefully you won't lose any data. Then you can put your other cards in. One at a time is nice because you can better control putting in the drivers without XP deciding to put in the ones that they want.
Eventually XP will tell you that you have to call MS to reinitialize your product activation. Apparently it gives you an 800 number and is no problem when you tell them hat you have done.
Good luck and enjoy the video work. Toni Hackler. a Moderator in number of the forums, does a lot of Video work with her 3.0 Intel P4. You might want to exchange knowledge. The mods all post their CNET email address.