I have seen major problems with changing out OEM motherboards to different or upgraded motherboards. The manufacture routinely stamps the OEM system disks with a 'tattoo' code that binds the OEM release to that specific system so when you upgrade the motherboard you may loose that tattoo and thus will find the OEM Windows disk to be completely useless.
Worst case is the disks from HP/Compac, as they are basically System Images rather than installation media. Trying to repair a previously installed OS with them is most difficult and not advised if you have changed out major components with anything other than direct factory replacement parts.
Good luck with the situation.