barcode reader: how to trigger a command after a scan

[van12]

hello

how can I make my PC displays a picture after I point my barcode scanner at a barcode, just like

if id="100" exec i_view32.exe c:\pics\id100.jpg ; if the barcode is 100, it shows the pic id100.jpg
if id="101" exec i_view32.exe c:\pics\id101.jpg
if id="999" exec i_view32.exe /slideshow=c:\pics\*.* /closeslideshow ; if id=999 loop the whole directory

nb: I use irfanview

Is there any shareware/freeware which can handle it? if not, please give me some hints how to code it in VB or .net or perl/linux

Tuan