We've already send a radio message to the Gliese 581 system
It will be arriving in the year 2029:
http://en.wikipedia.org/wiki/A_Message_From_Earth
20,500 years for a probe to get there? Unless this is a multigenerational
colonization starship, I don't quite see the point of something that slow.
An Orion nuclear pulse engine could probably get a probe there in much
less time using feasible technology.