Anyone know the best way to determine whether the user is running windows7?

I have methods for isWindowsXP and isWindowsVista:

Code:
Function IsWindowsXP() As Boolean
    
Dim osvi As OSVERSIONINFO
Dim strCSDVersion As String
Dim MajorVersion, MinorVersion, ServicePack, PlatformId

osvi.dwOSVersionInfoSize = Len(osvi)

If GetVersionEx(osvi) = 0 Then
    Exit Function
End If

strCSDVersion = StripTerminatorOS(osvi.szCSDVersion)

MajorVersion = osvi.dwMajorVersion
MinorVersion = osvi.dwMinorVersion
ServicePack = strCSDVersion
PlatformId = osvi.dwPlatformId

Const dwMaskXP = &H2&
    Dim XP
    XP = (PlatformId And dwMaskXP)

If MajorVersion = 5 And XP Then  'XP

    IsWindowsXP = True
Else
    IsWindowsXP = False
End If
'MsgBox "IsWindowsXP=" & IsWindowsXP & vbCrLf & " MAJOR VER=" & MajorVersion & vbCrLf & " XP = " & XP & vbCrLf & " PlatformId = " & PlatformId & vbCrLf & " MinOR VER=" & MinorVersion & vbCrLf & "ServicePack=" & ServicePack
End Function
Code:
Function IsWindowsVista() As Boolean
    
Dim osvi As OSVERSIONINFO
Dim strCSDVersion As String
Dim MajorVersion, MinorVersion, ServicePack, PlatformId

osvi.dwOSVersionInfoSize = Len(osvi)

If GetVersionEx(osvi) = 0 Then
    Exit Function
End If

strCSDVersion = StripTerminator(osvi.szCSDVersion)

MajorVersion = osvi.dwMajorVersion
MinorVersion = osvi.dwMinorVersion
ServicePack = strCSDVersion
PlatformId = osvi.dwPlatformId


Const dwMaskVista = &H2&

    'MsgBox "dwMaskVista: " & dwMaskVista, vbOKOnly 'mk
    
    Dim Vista
    Vista = (PlatformId And dwMaskVista)

If MajorVersion = 6 And Vista Then  'Vista

    IsWindowsVista = True
       
Else
    IsWindowsVista = False
    
End If
End Function
Currently, when running windows7, isWindowsXP returns false and isWindowsVista returns true. Ideally I need both to be false, and a new function isWindows7, which would return true.