What is the perception of doing a conference presentation at your own institution as opposed to another one?
Rtisan is probably right about a local conference carrying somewhat less weight and prestige on a CV.

However, there are some other benefits of presenting at a local conference:


It's usually free.  With the travel money you save, you can attend another conference far away later on.  Now you have two conference talks on your CV instead of just one.  (In other words, "present locally" versus "present far away" is probably a false dichotomy.  Even if the local conference conflicts with a faraway conference, there is very likely another faraway conference in the near future that's just as good.  And if the conflicting faraway conference is, like, the one and only awesomest conference in your field, then the organizers of your local conference probably shouldn't have scheduled theirs to conflict with it.)
Less travel: you get to save a day or two of travel time, sleep in your own bed, see your family, etc.  This may make the conference much more relaxing.
Being the attraction: People may be saying to themselves: "Hey, there's a conference at Podunk University.  I think that's where gman works, so I'm sure he'll be there.  I was just reading his paper and it will be great to hear his talk and ask him questions."
Networking: as a local at a conference, people are more likely to want to talk to you.  For instance, "Hey gman, you live here, can you recommend a good restaurant in town?  Would you like to join us for dinner?" The opportunity to talk to other researchers informally can be very valuable to a career.  Even fielding mundane questions like "How do I connect to the wifi?  Where is Room NNN?  Can you help me turn on the projector?" can start good conversations.  (Make sure you know the answers to these questions!)  It can be harder to initiate interactions like this when you are a stranger in a strange city.
Help organize: Try to join the organizing committee, or at least offer to help them out.  Organizing a local conference is a lot of work, and by contributing to this you will gain the appreciation of your colleagues.  It's also valuable experience, and "conference co-organizer" is a nice line to have on a CV.  Finally, conference organizers tend to have more contact with the visiting participants, contributing to Networking as above.