Yeah, I'd check that power supply, as well. Power supplies seem fond of blowing up when any kind of hardware is changed, and they'll cause RAM errors to be detected before they totally fail.
Now, if the power is known good, next thing I'd attack is the software. Most likely there is a driver conflict / or one of the more advanced copy protection schemes went awry. If that's the case, though, the only real solution would be to format/reinstall. I've not seen a Windows build properly recover after that kind of a conflict, especially if it is involving some DRM that went wrong. (VERY LIKELY) See some of the newer DRM routines (which are silently and automatically installed with many new shrink-wrapped programs!) install phantom CD devices into the registry, etc... Swapping out a CD drive can cause those DRM drivers to crash, basically leaving your windows box totally hosed until a complete rebuild.
Those are the two most likely things. Really, I'd suspect it's #2, but #1 is easier to check. ;-) I highly doubt it's something wrong with your motherboard.