I am currently using on-board audio and am looking for a sound card best suited for competitive FPS gaming. I'm into older games, sure, but if it's better in newer games, then that's really what matters. My budget really is whatever, but I'm not spending more than $150-ish give or take unless...

Quick question:   I use a pair of AD700's. I place competitive gaming in the highest regard and I'm not sure if the Sound Blaster Z is better than the X-Fi Titanium HD or not. I seem to have mixed reviews on which has best headphone surround, and perhaps the HD has better actual sound quality...