If you configure the raid within Windows restart your machine hit F8 before the windows screen to bring up the boot menu. You might need to continue tapping it slowly while the system is coming up. Then choose last known good configuration.
This should put you back in business.
If you configured the raid from the systems bios you will need to go in and undo what you did. The system will then boot properly.
What kind of raid did you set up and what did you want to acomplish. Let me know and maybe I can walk you through it.