I recently put together a high-definition Vista based media PC system and thought I should share the things I discovered along the way.

I wanted to build a media player for the lounge that would play DVD, HD-DVD and Blu-ray discs. Via a network and the internet, it needed to be able to stream video and audio files, and finally allow the viewing of digital photographs. I wanted it to look like a quality piece of AV equipment and not a PC. For video it needed to connect to my existing 40inch 1080p LCD TV via an HDMI cable and for audio, my existing home theatre system via a digital optical SPDIF (Toslink) connection.
 

Although I had put together many PC's in the past, this one was different. This time its size, appearance and noise levels were more important than the internals. It had to look the part, be the right shape and size and not emit countless decibels of fan noise in operation. Also it needed to switch on like a DVD player, be ready to do its thing as quickly as a DVD player and be remote controlled.

So the most important things were:

A nice looking case was obviously required. I looked around determined that it should look nothing like a PC stuck under my TV. After a long search, I found a good case from Antec (Veris Micro Fusion with 350W PSU) that was perfect for the job. It has a built-in display and includes 4 fans, 3 of which are manually speed adjustable, the fourth is speed controlled by the power supply.
I wanted to use a motherboard with on-board graphics to reduce noise and cost but it just was not up to the job at 1080p 60Hz resolution. The board I selected was a mATX Gigabyte motherboard with on-board 7.1 channel audio and the AM2+ socket (for AMD Phenom processors).
The case can only take low-rise expansion cards, so I used an MSI 8600GT 256MB PCI-E graphics card which gives great performance.
I fitted an AMD Phenom X3 Triple Core 8450 2.1GHz processor and 2GB (2x1GB)of DDR2 1066MHz memory.
 
To read as many disc types as possible I fitted an LG Electronics Blu-Ray & HD-DVD-Rom Combo DVDRW SATA drive, the best choice by miles for the price.
Finally I fitted a Western Digital Caviar SATA2 hard-drive, known for it's really quiet operation. As I wasn't going to be recording, I didn't need the space, so selected a really reliable and stable 250GB version. (If I choose to add recording later, I'll add a large second drive to keep my recordings away from the operating system.)