well like i said, I've just barely started using VBA and Access, but what I tried was along the lines of
If [cboA]="Yes" And [cboB]="No" Then
DoCmd.OpenForm "A", acNormal, "", "", , acNormal
If [cboA]="No" And [cboB]="Yes" Then
DoCmd.OpenForm "B", acNormal, "", "", , acNormal
If...