I would recommend Ubuntu 8.04 or 8.10 if 8.04 doesn't support your hardware out of the box. Use the i386 32bit versions, NOT the 64bit x64 versions, unless you know what you're doing and are technically adept. There is NO current practical, day-to-day benefit in using the 64bit OS's for anyone using less than 4GB of RAM (i.e. most people and most media PC's)
If you want to control a tuner card or tuner box, install Mythbuntu from the Synaptic GUI (Add/Remove programs for ex-Windows users). You then set up MythTV via the Mythbuntu Control Center GUI in a very wizard-like fashion. Don't install Myth/Mythbuntu if you don't need to control tuner cards/boxes. I've installed Mythbuntu from Synaptic on top of Ubuntu 8.04, but haven't tried it from Ubuntu 8.10 yet.
If you want a media-center like front end for photos/music/random video files/DVD/CD, install XBMC from their PPA repos, follow instructions athttp://xbmc.org/forum/showthread.php?p=185738
If you don't want/need a media-center style front end for media playback, just install SMplayer and the latest VLC via either Synaptic (VLC) or the SMplayer repo:http://smplayer.sourceforge.net/downloads.php
Use VLC for DVD playback and SMPlayer for all other video files, though the latest VLC 9.x plays great with most video files, too.
You should install ubuntu-restricted-extras from Synaptic first, as well as the w32codecs from Medibuntu (follow instructions copy/paste at):https://help.ubuntu.com/community/Medibuntu
Plenty of other apps available for desktop style photo viewing and music management/playback:
Music: Audacious (classic Winamp 2.x style), Banshee, Amarok, Songbird, or Foobar under Wine, etc. SMplayer and VLC play music fine, too.
Photo Viewing/Slideshow: GPIcView, GQview, gThumb, mirage, Gwenview, Picasa, or IrfanView under Wine,etc.
To address some of zim2dive's issues:
In the 20+ years I've been building PC's, from DOS through Win3.1/95/98/98SE/XP and now linux, I've *always* had to install audio, video and network drivers after the initial OS install from its CD/disks. In fact, since switching to Linux, I usually only need to install the video driver for Nvidia via the auto-popup in Ubuntu 8.10, or at worst via the third party EnvyNG simple GUI in Ubuntu 8.04. Either way, ATI and Nvidia video driver install in Ubuntu is trivial.
An argument could be made that audio driver and network driver (Ethernet or wireless cards) installation/updates could be made simpler in Ubuntu/Linux, but that's a separate issue, and subjective. Most of the time for most people, wired Ethernet and audio should work out of the box, and wireless cards if you selected the wireless card for Linux compatibility in the first place- lots to choose from at newegg.com, just search the reviews for each wireless PCI/PCIe/USB card for "linux" to determine compatibility:http://www.newegg.com/Store/SubCateg...eless-Adaptershttp://www.newegg.com/Product/Produc...Keywords=linuxhttp://www.newegg.com/Product/Produc...Keywords=linuxhttp://www.newegg.com/Product/Produc...Keywords=linux
An OS-agnostic method (i.e. no wireless drivers needed) to add wireless to any computer with a wired Ethernet port is to use a Wireless Access point in Bridge mode connected to the computer via an Ethernet cable- a good, simple method to add wireless to a stationary media PC, with the benefit of locating the antennas for best reception:http://www.newegg.com/Product/Produc...82E16833156159http://www.newegg.com/Product/Produc...82E16833156232http://www.newegg.com/Product/Produc...82E16833203004
Flash install in Ubuntu 8.04 or higher is trivial- just install via the popup in Firefox when you hit a page that needs Flash (other than Youtube- YOutube is fine after the inital Flash install). Try pogo.com for the Java and Flash auto-popups in Firefox to auto-install Flash and Java. In Windows, I always had to browse to adobe.com, find the Flash installer, download it, then run it. Then do the same for Java at sun.com, if you could comprehend their site and versioning logic
In Ubuntu/Firefox, it's all automatic.
Anyone who's been doing media PC's/HTPC's since the late 1990's knows that it took several years just to get reliable SPDIF output from Win98SE/XP- it wasn't until around 2002/2003 or so that SPDIF output became stable and relatively easy to enable in Windows. I was amazed how trivial it was to enable SPDIF passthrough on Linux the first time I tried last year. By these measures, I'm amazed that HDMI output is so far along in Linux given the relatively short time HDMI ports have been on common PC hardware...