Cheapest recommended combo for HD media?

Just a general question here.

I am to set up computer in a clients new 'sports/game room' that has a purpose of streaming his High Def video's/Internet streaming content/DVD's to his extremely expensive FD-151 Plasma.

His current computer is a Dell, about 6+ yrs old. I believe it runs about 2Ghz on a single core.. with integrated graphics. So the streaming of HD Movies/Content is not up to par.

Given the only other duties for this machine are to browse the web, check email and such.. (No gaming, or intense applications) -- What would be the cheapest build or pre-build that would get the job done?

Slim design is a plus.

Don't want to chance anything that has the possibility of running anything less than perfect, because the quality of the stream has to be 100%.

Also on the subject, I recommended he utilize some sort of LCD monitor (no matter the size) along with the 70inch Plasma (he wanted to just have computer to plasma).. but I recommend this dual setup to make selecting and just general tasks easier to deal with. (IE: If watching DirectTV on the plasma, you don't want to change inputs to see what is going on with the computer).

With that in mind,.. any creative ideas for monitors? The goal is something out of the way,.. if seen, then not too bulky. Be nice to have the monitor hidden, or if in plain sight (which I imagine it needs to be) -- be of some design that adds to the room not takes away. (Wood (grain) paneling on the walls,.. pool table, leather couch, clean setup of Plasma/Bluray/Wireless -- very elegant look to the room.)

Thanks for any ideas!

Welcome to the forums.

Some HTPC cases come with small few inch LCD screen on the front, saw one bigger screen which retract into the case like a CD tray when not needed, these could do depending on budget and what use actually that screen would get.

With integrated gpus accelerating flash and most video formats the hardware doesn't have to be really fast. Even an IOn could do.

Would recommend an AMD system as mobos are cheap just like their 45nm processors even quads under 100$ in case he would use it to transcode something. but with the current flash results I can't do.
Maybe it could still work with an additional vga like the new cheap GT 210 or 220, probably something older would still work, preferably a fanless card.

Can't really tell you what would be the bare minimum for it as I use higher end cards, but compared to what decent HTPC cases cost it won't be significant.