I dont know of any realy good HTPC boxes. Most media extender type of equipment are designed to be too low end and for singleness of purpose. It is hard to find a truly flexible htpc, that is also a general use computer. Just build a low-end PC and maybe add an inexpensive HD TV Card.
I dont think you really need a video card. An i-3 2105 would give you a nice flexible processor that has the Intel 3000 HD Graphics. That and a motherboard with one or two HDMI/Displayport outputs might make a nice device you can access the internet with. If you want Cable or satelite TV you can use an HD TV card with your cable box, or you can access your VCR/Blu-Ray device. I have not been willing to pay for TV much because it is just getting too costly, and there is too little on that is watchable. Who wants to watch government brainwashing channels anyway? I built a computer in my signature for just around $700. You can probably cut about $100 off the price by just using a i3 processor or to use one of the lower end processors for around $60-$90 depending on the model. Sometimes Frys or Micro-center stores have low-end Processor Motherboard combos. I just built mine in an Antec 300 case because that case was on sale with a 430 watt power supply. That case also has fans with 3-way speed switches, so you can turn down the fans to lowest speed to reduce noise.
Dont know much about pre-built.
Some people like these DELL Inspiron 620 ST because you can lay them down on their side and put them in a console cablinet like a BLUE-RAY. I dont really think they are that good. But you can get them in the low watt version processors. They should have a version with the HD3000 graphics, but that is not an option. However, I think you can get a Radeon video card also, or just add one on your own later with HDMI.
I think some companies like happaug (Spell) sell some DVR type of HD media extenders that can access the HDTV and let you record it on your PC.
I think Direct TV has an IP based TV service that might be nice if you want TV. It is part of their new U-VERSE launch.
There is an option on newegg.com where you sign up for the newletter deals. You have to get the newsletter to get the deals and you need the codes from the newsletters to get the deals.
For instance there was a combo deal going on for a gigabyte mb, 4 gigs of hyperx ram and an i3 2120 for 194.99 -- Seems like a good deal.
Might make a nice grandma or htpc kit.
The i-5 2500k is also on sale for 204.99