Crossfire help

Got two shiny new graphics cards.

1) Uninstalled old drivers.
2) Turned box off.
3) Took out the old graphics card and put in ONE of the new ones.
4) Booted up.
5) Windows freezes on startup.  Be in in normal mode, safe mode, ot even the recovery console.

What now?

1. put old card back
2. reinstall old drivers
3. took out old card and put new without uninstalling of old drivers
4. ???????????
5. profit