Puoi usare le API di Win.
Ecco un semplice esempio (Nota: l'ho copiato da "Api-Giude 3.6")
codice:
Const CCDEVICENAME = 32
Const CCFORMNAME = 32
Const DM_PELSWIDTH = &H80000
Const DM_PELSHEIGHT = &H100000
Const CDS_TEST = &H4
Private Type DISPLAY_DEVICE
    cb As Long
    DeviceName As String * 32
    DeviceString As String * 128
    StateFlags As Long
    DeviceID As String * 128
    DeviceKey  As String * 128
End Type
Private Type DEVMODE
    dmDeviceName As String * CCDEVICENAME
    dmSpecVersion As Integer
    dmDriverVersion As Integer
    dmSize As Integer
    dmDriverExtra As Integer
    dmFields As Long
    dmOrientation As Integer
    dmPaperSize As Integer
    dmPaperLength As Integer
    dmPaperWidth As Integer
    dmScale As Integer
    dmCopies As Integer
    dmDefaultSource As Integer
    dmPrintQuality As Integer
    dmColor As Integer
    dmDuplex As Integer
    dmYResolution As Integer
    dmTTOption As Integer
    dmCollate As Integer
    dmFormName As String * CCFORMNAME
    dmUnusedPadding As Integer
    dmBitsPerPel As Integer
    dmPelsWidth As Long
    dmPelsHeight As Long
    dmDisplayFlags As Long
    dmDisplayFrequency As Long
    dmICMMethod As Long 'NT 4.0
    dmICMIntent As Long 'NT 4.0
    dmMediaType As Long 'NT 4.0
    dmDitherType As Long 'NT 4.0
    dmReserved1 As Long 'NT 4.0
    dmReserved2 As Long 'NT 4.0
    dmPanningWidth As Long 'Win2000
    dmPanningHeight As Long 'Win2000
End Type
Private Declare Function ChangeDisplaySettingsEx Lib "user32" Alias "ChangeDisplaySettingsExA" (lpszDeviceName As Any, lpDevMode As Any, ByVal hWnd As Long, ByVal dwFlags As Long, lParam As Any) As Long
Private Declare Function EnumDisplayDevices Lib "user32" Alias "EnumDisplayDevicesA" (Unused As Any, ByVal iDevNum As Long, lpDisplayDevice As DISPLAY_DEVICE, ByVal dwFlags As Long) As Boolean
Dim OldX As Long, OldY As Long, T As Long
Private Sub Form_Load()
    'KPD-Team 2000
    'URL: http://www.allapi.net/
    'E-Mail: KPDTeam@Allapi.net
    Dim DD As DISPLAY_DEVICE, DevM As DEVMODE
    DD.cb = Len(DD)
    OldX = Screen.Width / Screen.TwipsPerPixelX
    OldY = Screen.Height / Screen.TwipsPerPixelY
    'First retieve some display info
    If EnumDisplayDevices(ByVal 0&, 0, DD, ByVal 0&) Then
        'and show it
        Me.AutoRedraw = True
        Me.Print "Device String:" + Left$(DD.DeviceString, InStr(1, DD.DeviceString, Chr$(0)) - 1)
        Me.Print "Device Name:" + Left$(DD.DeviceName, InStr(1, DD.DeviceName, Chr$(0)) - 1)
        Me.Print "Device Key:" + Left$(DD.DeviceKey, InStr(1, DD.DeviceKey, Chr$(0)) - 1)
        Me.Print "Device ID:" + Left$(DD.DeviceID, InStr(1, DD.DeviceID, Chr$(0)) - 1)
    Else
        Me.Print "Error while retrieving Display Information"
    End If
    DevM.dmSize = Len(DevM)
    'we want to change the horizontal and the vertical resolution
    DevM.dmFields = DM_PELSWIDTH Or DM_PELSHEIGHT
    DevM.dmPelsWidth = 640
    DevM.dmPelsHeight = 480
    'change the display settings
    Call ChangeDisplaySettingsEx(ByVal 0&, DevM, ByVal 0&, CDS_TEST, ByVal 0&)
    T = Timer
    Do: DoEvents: Loop Until Timer > T + 5
    DevM.dmPelsWidth = OldX
    DevM.dmPelsHeight = OldY
    'change the display settings back to the old settings
    Call ChangeDisplaySettingsEx(ByVal 0&, DevM, ByVal 0&, CDS_TEST, ByVal 0&)
End Sub
Copialo in un form e lancia il programma.

Spero ti serva.
Ciao.