try this....Open the Boot.ini File
1. Right-click My Computer, and then click Properties.
-or-
Click Start, click Run, type sysdm.cpl, and then click OK.
2. On the Advanced tab, click Settings under Startup and Recovery.
3. Under System Startup, click Edit.
just delete the line with the vista choice on it.....should work, but no guarentees....use info at your own risk! i had two choices for xp once, and this got rid of one of them so that screen didn't show anymore at start-up.