The problem is none of those apps are integrated, and they all lack functionality the iLife suiite has.
If I plug in my digital camera to a Linux box, Gimp doesn't automaticially pop up and ask me to import photos, nor does it asisst in organizing them, or allow me to order prints or a photo book. It is simply a photo editor, and a highly complex one for simple photo managment.
Kino is indeed a movie editor like iMovie, but lacks the integration features. iMovie allows me to see my entire photo collection as set up in iPhoto, and also my iTunes collection for adding background music without digging through the file system. Out of all the applications named, this one does look to be the one most similar to the iLife offering though. So you have DV movie editing covered thus far.
XMMS lacks any importing ability without extra plugins, and also lacks the organization of iTunes. It simply plays back media. Some may also find the lack of an online music store a negative, but I personally still buy physical media to then turn into digital files.
Audiocity seems to be a wave editor only, and not a music creation tool/tracker. I can't see how to attach a MIDI keyboard to AudioCity to record a track for a complete song.
And your list is missing something comparable to iDVD (iDVD sets up DVD menus, DVD slideshows and burns to disk.)
And again, none of the apps you talked about work togther in a seamless way. I'll give you the list of steps to import photos and burn them to a DVD slideshow on a Mac, go ahead and give me the comparable steps on Linux. Make sure to start from the point of starting the system for the first time.
1. Unpack computer and power on
2. Go through registration to set up the first user account. Consists of next a few times and typing in your name.
3. Plug in the digital camera either via USB, or a media reader.
4. Type a name in for the roll of photos you are importing, as iPhoto autolaunched when you plugged in the camera.
5. Click import and wait a few moments.
6. Title the photos if needbe. Also do any quick editing like straightning them out, removing red eye, adjusting the color balance.
7. Click Share - send to iDVD
8. Click the theme for the DVD menu on the left. Add in photos or music from your collection via the media button.
9. Select transition that you want between photos and any background music from the iTunes collection.
10. Click burn in the bottom right, and put in a DVD-R when prompted.
And to reiterate, Apple is not likely to ever offer a system you are happy with, nor is HP, Dell, or Sony. Posting here about wanting such will do nothing beyond disappoint you when it doesn't happen. Apple isn't a parts company, they won't ever sell a barebones system. If you want something like that, look into a Shuttle XPC box. I have been very happy with them as a desktop system, and with it you slap in your own hard drive, RAM, CPU, CD-Rom, and if needed, a better video card. Then once you get all the hardware togther, feel free to slap in your Linux cd, and get the system you are happy with. What you want is very possible to obtain. You just seem to be looking at the wrong place. Just as a new car dealer is the wrong place to go if you want to buy the engine, transmission, and other components of a car seperate from the body.