Serveral host broadcasting to port 1434

Hello,

I've just started playing with snort rules and created a new rule for the internal network that would grab any traffic on port 1434 "Microsoft-SQL-Monitor". The rule is now running and I see several desktop PC's sending out traffic to destination 255.255.255.255 port 1434. So my question is are these desktops compromised. I've seen references to a MS-SQL worm with activity like this. Any thoughts would be much appreciated.

Thanks