About the Link with the Extra tracks, I can confirm that they are definitely from .hack// GU, and were all from the game itself, Not the terminal disk, except for the 1st track. as to where they come from, they came on the CD that came with .hack//GU magazine The World vol.6.
The track 8
"Fu? Lotaif? From the Reflection" was the Original GU Theme for Skeith that was used in the prototype trailer, that was then scrapped for the Current theme, "I'm Right Here".
Track 7
"Early Town Image", Im not exactly sure, But I have heard it in game.
Track 6
"An Old Enemy Again?" is also in the game as well, But not sure about the legit OST. It's from this scene. The name itself gave it away to me.
SPOILERS
http://www.youtube.com/watch?v=VkSGDecHJZU
Track 5:
"To the Other Side of the Wall" is played whene
Spoilers
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Atoli uses the Tri-Edge SIGN at the end of the game to warp into the area with the locker.
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Spoiler end
Track 4
"Jyu - Ba - Chi!!!!" is the more slower and laid back version of Piros the 3rds theme that is used through the game with scenes with him. Like at the wall.
Track 3,
"Running Wildly to the End" is a slightly altered version of "Shino-Honeysuckle" which was based on the main theme of Saitan, "Yasashi Ryoute". This version plays at.....
SPOILERS
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in the scene right after you defeat Tarvos.
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End
Track 2
"The Name of Duty" is on the desktop as the BGM "responsibility". IIRC happens after the guild shop scene.
Track 1
Track one is from .hack//G.U. The World Magaine's Vol. 6 CD. It's the 1st track. It's Karl's theme for .hack//ZERO. Normally since it's a graphic novel it wouldn't have one, But in this case they made an exception. IMO, it's a beautifully done song easily on par with Yasahi Ryoute, Shinjitsu no Yukue, and surpasses vol.3s theme.