The Sapphire HD 4550 is a tiny little video card that will fit in any desktop PC with a PCI-E interface. The GPU is a smaller version of its bigger brothers, the 4800 series and the 4600 series. There are 80 stream processors, an incredible number for such a low-end GPU. Unlike most video cards in its class, the 4550 has active cooling.
Also pretty incredible, the HD 4550 sports 512 megs of memory, in four 128mb Samsung DDR3 chips. I don't know that you will find 512mb of memory in any other video card in this class.
As I mentioned earlier, the Sapphire HD 4550 is considered a "low-profile" card. The card is configured so that with a normal PCI expansion bracket, the hard has a DVI connector, an S-video connector, and a Sub-15 connector. To convert the card to low-profile, you unplug the Sub-15 connector, remove the regular expansion bracket and replace it with the included LP bracket.
The Sapphire Radeon HD 4550 includes a nice bundle considering the card's price. Included are Sub-15/DVI and DVI/HDMI adapters, S-video/HDTV cable, S-video/coaxial adapter, and the LP expansion bracket.
So what is the market for this video card? I'd say a very low budget multimedia rig or a mini computer. The card would be an excellent choice for an HTPC rig, especially with its native Blu-Ray decoding, 1080p resolution, and ATI's built-in HD Audio, allowing 7.1 audio via HDMI cable, and for that reason, a viable upgrade for an HTPC rig with integrated graphics. Let's face it, though you probably could play some older high-end games, and struggle through some more modern DX10 games, this card is not intended for gaming, except Windows games like Spider Solitaire, and probably games like Zuma or Luxor.
Installation is a matter of popping the card into the PCI-E slot. If the card is to be installed in a Low Profile configuration, unplug the Sub-15 connector and install the LP bracket. Installing the Catalyst drivers in Vista is always hit or miss, I highly recommend using the driver disk first. With my first installation, the card freaked a little when I raised the resolution to 1680 x 1050, due to a driver issue. Everything was fine after uninstalling and reinstalling the Catalyst suite.