XBOX360 + 5.1

Anyone else got their 360 setup to use 5.1 surround? I recently replaced that
normal audio cable that comes with the 360 with an optical cable to my amp and
the difference is amazing, and unlike my mums playstation 3 the xbox's audio
output actually works properally (the ps3 refuses to send pure bitstream to the
amplifier for decoding) 

The best example i've been able to find for 5.1 in a game is the orange box
(collection of the half-life 2 games and a few bonus games, well worth it) for
instance you can walk around someone talking and you can hear their voice
panning around with you. 

What other titles should I be looking out for?

 

 

(ps the hive seems very very very slow atm)

I've been running 5.1 since launch.  Gears of War and Call of Duty 2/3 were fun
games to play in 5.1.  Shooters in general are good because there's often
commotion happening behind you and to your sides.