So my brother in law recently got me a free 55 inch rear projection tv from this lady whose moving back to england, very nice and High Definition. If I were to get the eMac a Mini Display port to HDMI adapter would the eMac be able to use it?
No. The eMac only has Mini-VGA as an output, which you can convert to VGA, then further convert to Composite, Component, or S-Video, but you cannot, without spending a lot of money, convert it to any digital signal (DVI or HDMI).
As the previous post indicates, yeah itd be quite spendy and the connection may or maynot endup working really well.
Id scratch that, save up andjust get a refurb MacMini ive seen em in the apple online store for about $450 or so, pretty good deal.