There is not any guarantee but it has (and hasn't) worked for me. Most recently, I swapped from ATI chipset to SIS chipset mobo, all other components the same, on XP MCE and it worked just fine. The biggest potential issue is the HAL/PC type but if you're using a relatively new mobo with APIC support like Intel P35, Windows should be running in APIC mode that will be compatible with any new mobo.
Second issue is storage controllers. This can usually be addressed by uninstalling any hardware-specific drivers and changing to in-box Windows drivers. I would suggest IDE mode for SATA in BIOS.
Uninstall drivers for all devices such as audio, LAN, modem, then disable them in BIOS or remove them before swapping.
When you first boot Windows on the new mobo, boot into Safe Mode. Let Windows automatically install new devices until you are prompted to restart. You might want to have a PS/2 mouse or keyboard handy, in case the USB controllers don't work the first time around.