<p>I would agree with the salesman. VGA signal is not very strong, stick it with wireless, which is also not very strong, and you've got a recipe for disaster.</p>
<p>In both my previous and my current church they have a long VGA cable that goes from the computer to the data projector, and it's actually fine. I thought they'd need a repeater after about 20/25 metres (sorry, don't know feet), but they work fine at about 30-40 metres.</p>
<p>Wires are maybe "not cool" and sometimes get in the way a little, but they are still the most reliable way to get your signal where it needs to be.</p>