Just to clarify things, since there is some misleading info in this thread:
1) The CD that comes with the MB is almost certainly NOT bootable, it just contains drivers and software.
2) The old hard drive with Windows on it will almost certainly NOT boot properly when installed in the new system. The reason is that Windows installed MB- and CPU- specific boot drivers on the old hard drive which are specific for the hardware it found in that system. Your new MB/CPU are almost certainly different (it IS an upgrade, right?).
One thing you can do is boot from the Windows CD, and choose to do a "Repair" Installation on the hard drive. This approach *should* achieve what you are trying to do, but doesn't always work 100%.
Best performance and compatibility is to "start fresh" by installing Win on an empty hard drive. You can then copy your data onto that drive, but will have to *reinstall* all your software from scratch, so it's a fair bit of work. On the plus side, you'll not be installing old unused files/drivers/programs that were cluttering up things, so the system should be faster and more stable.