The two-disc version is essentially the less shiny version of the limited Legendary Edition. It features music from all three of Blizzard's franchises: Diablo, Warcraft and, of course, Starcraft, as played by the Eminence Symphony Orchestra and special guests including Kow Otani (best known for his score from PS2 game Shadow of the Colossus).
Even better, if you've not picked up the set yet then there's a special $5 discount for orders made before the relaunch date next month, dropping the price from $24.95 to $19.95. Just head here to order. Copies begin shipping today and will also be made available through stores next month.