So you want to add a good video card, at a budget you can afford, to your home theater PC to let you view the movies in a best possible manner? To start with, for the sake of best performance over the system bus let us consider only the PCIe bus. The original PCI is quite sluggish compared to what these PCI express cards can do. If you want to view HD movies, you want to provide for speedy communications with your video card with rest of the system such as the main processor and the system memory.
What You Need in the Right Cards
Be very clear about what you are looking for. In this instance we are not looking for a high performance graphics card that gives me the best gaming experience. Instead, what we are looking for is a card that will play commercial movie DVDs and DVDs from other sources without a problem. We need support for the HD movies. So, that means support for playing the Blu-ray discs too. So first thing to ensure would be that your home theater PC does have a drive that can play Blu-ray discs that play 1080p true HD video. Your video card should be able to support real-time de-compression of the latest MPEG4 and H.264 codecs. Be absolutely clear about the price/ performance range you are aiming at.
Your PC monitor, even if you have a 19" one, is not the best display for such high resolution videos. Therefore, you are likely to be tempted to play the video in the home theater in your den. The video card you choose then should have a suitable connector for doing so. The ideal would be an HDMI connection. The next best thing would be a set of component video connectors and suitable audio connection or at least a DVI connector. HDCP support would also be required.
Some Sample Good Products
Bizrate, Shopping.com(https://www0.shopping.com/xCC-PCIe_Video_cards~FD-0~LO-1~DL-0~SK-0~PG-4), Newegg.com and Shopping.com are some sources where you get to compare a lot of products. Discussed below are a sampling of products at a particular price point that is considered the most comfortable pricing.
HIS H260XTP512DDN-R Radeon HD 2600XT from Hitech card earned a review of 5 star from 68 users reviews. At under $100 is good value for money for the product you are looking for if you are on a limited budget. It has 512 MB memory ion board. Larger amount of memory on board buffers incoming video data and generally larger is better. The memory bus is 128 bit wide which spells fast speed on data transfer with GDDR3 memory. It supports HDCP. It has HDMI and DVI outputs.
PNY VCQFX370-PCIE-PB Quadro FX370 is another good product at $124.99. This is another 5 star product at the same shopping site. It has 64 bit wide memory bus with 256 MB of on board video memory. Performance wise likely to be a little below the performance of the first product discussed.
VisionTek RADEON HD 4670 is a 1 GB, DDR3 memory card and is available for $95 to $140 depending on where you look. This earned a 4 star review rating from more than 8000 users at Best Buy. The manufacturer clearly mentions support for all the relevant compression technology as well as 7.1 surround sound. HDMI, Component video and DVI connectors supported.
The above are samples of what products are available. The sites indicated give you the opportunity to do comparative shopping but do check out the manufacturer page to get a clear idea of the specs and before finalizing on one. All three sites have products in different price ranges. $100 to $150 was taken to be the consumer sweet spot and we looked at only products in that price range.