I have found this little code snippit to be quite handy for converting all letters to upper case as they are entered into the field. I like this one because it doesn't matter if the user has caps on or off.
Sub txtData_KeyPress(KeyAscii As Integer)
KeyAscii = Asc(Ucase(Chr(KeyAscii)
End Sub
Sub txtData_KeyPress(KeyAscii As Integer)
KeyAscii = Asc(Ucase(Chr(KeyAscii)
End Sub