If you use the GetAsyncKeyState API, you will be able to have more flexiblity. The standard KeyDown or KeyAscii will not allow you to press more than 1 key at a time, this will.

Code for a module.
Code:
Declare Function GetAsyncKeyState Lib "user32" (ByVal vKey As Long) As Integer
Code for a Timer. Set the Interval to 1.
Code:
Private Sub Timer1_Timer()

    If GetAsyncKeyState(vbKeyLeft) Then Image1.Move Image1.Left - 100
    If GetAsyncKeyState(vbKeyRight) Then Image1.Move Image1.Left + 100
    If GetAsyncKeyState(vbKeyUp) Then Image1.Move Image1.Left, Image1.Top - 100
    If GetAsyncKeyState(vbKeyDown) Then Image1.Move Image1.Left, Image1.Top + 100

End Sub