SoftwareUpdate with simple user...

Hi guys,
this is my first post, and I need help :lol:
Well, I wrote the following script to allow non admin user check software updates ad possibly schedule the operation with iCal.

set theDate to date string of (current date)
set updateresults to do shell script "softwareupdate -l 2>&1"
say "software update report"
display dialog updateresults with title theDate ¬
   with icon caution

Now I’d like to modify my script, because I wanna an alert if there are software updates and nothing if there aren’t. Please, can you help me? Sorry for my bad english, I’m trying to improve. Have a nice day