Well, if you can Post and get to the windows loading screen, it can't be *too* bad... Though a lot of people could tell you those can be the most frustrating problems. Forgetting to plug wire "A" into connector "1" issues are easiest to solve. But if that was the problem, the system usually wouldn't even post. Check it anyhow, though.
(1) Make sure you have the latest Bios
(2) Double check that everything is seated properly.
(3) If you have an overclock going, (which is pretty doubtful since you haven't gotten to your OS yet), reset your Bios to stock
Which version of Windows is it? I can tell you from personal experience that Vista gets unhappy when the Mobo changes. So what you are seeing might be Micro$$oft Licen$$ing detecting the change, and tossing a nuke in the works. In that case, set your boot to your CD/DVD, start the system on your Windows installation disc, and select "Repair Installation" (lower left corner). It may want you to redo your license key. If you don't have it handy, you can call Microsoft and they'll give you a new one: Just so long as you tell them you aren't using the OS on multiple PC's.
Know that there's a possibility it might want you to reinstall the OS, though. As you can imagine, it's a huge disruption that'll also force you to reinstall (and relicense!!) all your apps. Having said that, Vista will detect the previous installation and put your data into a folder marked "Windows_Old". So you should be able to rescue your saved games, pictures, music, and the like. In my case, the habit of saving the zip files of the things I downloaded paid off. Still had to rescue license keys, tho.
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