Need help setting up a whole house media system

First word of caution: Verify Receiver ID number (RID) of anything you buy on any auction site with DirecTV before buying. Almost all DirecTV equipment is now leased, and if you buy a leased unit (other than from a valid dealer) you will not be able to activate it. If you are able to find legitimate used owned equipment, great - but make sure you confirm that (by RID) before buying. You should also check the buy/sell forum of this web site.

If you want MRV (whole-home), then doing that via coax and DECA is by far the preferred method. That normally requires an installer and some equipment, but it can also be done via do-it-yourself. Either way, there is a monthly recurring charge for the service ($3 I think).

Definately do NOT buy anything from ebay unless you can verify with DirecTV that it is both owned equipment (the seller has the right to sell it) and can be activated on your account (possibly sometimes the owner owes DirecTV money and they won't activate the receiver even though they sold it to you) I find it best just to pay the lease fee and get a new unit from some place like solidsignal.com

for the videos on the XP machine. you could use a media server such as tversity to stream the videos to the DirecTV HD receivers.