http://www.youtube.com/embed/LVu53CSbCtw
How can no one have mentioned Frank Klepacki's stuff for C&C?! Also, best NES tune by far. It plays during the intro of MTG2, be sure to give it a go as it's fucking awesome. Good stuff to get the adrenaline going when gaming.
http://www.youtube.com/embed/0JwzwHB7Eng
.. and for some reason I can't make the videos show up in the post on the off-topic forum, whereas it works on the general forum o_O