I own both 5.1 headphones (from Zalman) and normal headphones with supposed "surround" effect from soundcard (CMSS 3D or others).
The surround effect works to some extend. You will NEVER have a convincing sound coming from behind if you don't have a real speaker behind. If you want real surround effects, get real surround speakers or headphones.
You really want to be "surrounded" by sound? You need speakers in front and behind you. Just one speaker for each ear won't do it, no matter how hard you try.
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SWTOR: 50 Jedi Shadow (Tank), 50 Sith Marauder (Annihilation).
LOTRO: Lifetime account, playing very casually.
WoW: Both accounts canceled for now.
GW2: Future Warrior.