The first thing to do is ensure Windows is in a state where it can work on the new system. In the case of 2000 and XP, this just means that it has to be able to access the hard drives.
To do this, replace the Bus Master drivers with standard generic drivers, as seen below. The drivers you need to be working on are found in Device Manager under "IDE ATA/ATAPI controllers". Ignore the Primary and Secondary, go for the other one. nForce users will only see one entry per controller.
If you're changing chipset (think in terms of drivers - Drivers for the VIA KT133 work fine with a KT400, but drivers for i815 won't work at all with an AMD760MPX), then you'll want to knock out the AGP drivers too to avoid video problems after the switch. Either uninstall them from the Control Panel, Add/Remove Programs or, in the case of VIA's 4in1, from the driver installation program.
The standard PCI to PCI bridge disables everything AGP, but also makes sure that old AGP drivers aren't around to screw your system up.
You should be good to go now, but it's worth it to do some more cleaning up. Remove both USB controllers (don't do this if you have a USB keyboard/mouse, duh) and uninstall your display drivers. Also uninstall any other non-critical drivers from the Add/Remove Programs in the Control Panel, or any other option your driver installer has. They'll need to be reinstalled anyway, since Windows has to reinstall devices if they change INT# lines and they will.
SATA INTEL NOTE
Now, go into Device Manager, select "Show Hidden Devices" from the menu, and enter Non-Plug and Play Devices.
Unless you now look under "Non-Plug and Play Devices" and delete "IntelIDE" and "IntelPPM", you will get a failure after the swap.
This is a problem with WindowsXP SP2's SATA drivers for Intel systems and is not present on AMD systems. Indeed, it only manifests when leaving an Intel system to go to an AMD one.
Finished all that rebooting? You're half way there.
Do your build and power it up. Windows will boot up and complain about drivers. Don't install any of them, just cancel every time. It'll do some automatically, these are probably the ones you don't have any drivers for anyway and you're quite happy to let Windows use the internal drivers.
Open a command line (Start>Run>cmd.exe) and take a look below...
With the devmgr_show_nonpresent_devices set to 1, and "Show Hidden Devices" enabled, you can see the trash left from your previous machine. Notice also the BDA deframers and filters and, off the bottom of the window, some Microsoft filters. Don't get rid of the filters, just the actual hardware that used to be in your system (or still is, you're reinstalling all the drivers). Just kill anything that's ghosted and not something you shouldn't kill like the filters and deframers mentioned above. You may be surprised by how much crap you find. Don't touch anything under Non-PnP Drivers or anything you recognise as a USB device. USB devices are 'reinstalled' on a per-root basis, as their location has changed, so you may see many duplicates, which is normal.
Next, let's get going. Install your chipset drivers first. Then the display drivers. It sucks to work in 640x480x16, doesn't it? Now go nuts. Install the drivers for everything and we're done. Remember to reboot every time you're prompted. Nothing screws up a driver install worse than the drivers not knowing what they need to know about the system.
We now have a clean system that doesn't even know you've changed the board.
