EXCEL: if Windows 7 then?

Hi,

I want to write VBA code in Excel spreadsheet, if the PC is using Windows 7 then run file C:\WINDOWS\Cursors\appsta2.ani, else (PC using Windows XP, Vista anyother Windows) run file C:\WINDOWS\Cursors\stopwtch.ani... so that the spreadsheet can be use in any Windows, as there is no 'stopwtch.ani' in Windows 7 cursor folder.

I think something like this;

Sub Wins ()

if Windows 7 then (i don't know how to write the code)
'do stuff for Windows 7
Else
'do stuff for others

End sub

How to write the 'if Windows 7 then ....' codes?