7.1 on headphones is...controversial. The jury is out.

Personally, I'm of the opinion you have two years. In real life you get orientation of sound from movement, like when a dog cocks his head, the same way you do in a game by rotating your character / avatar.

Where good "simulated surround" comes into play, is that in a given game, footsteps of an enemy, volume will vary based on their distance, but this is only supported with a "surround sound" compatible card or software set. Other instances of "simulated surround" simply run all sound through an equalizer, or add echos, to make it seem more "vibrant" or "alive."

This is all in lieu of a capable set of stereo headphones with a good dynamic range, meaning that when your speakers are crap, they're kind of shoe-horned into sounding "better".

True 7.1 headphones are a joke. 7 speakers in each ear? That is utterly not needed(not to mention the impossibility of a real sub-woofer). Because of the proximity to the ear, you do not need that to get a good range of sound.

Anything above stereo as far as earphones go, while technologically real(if not marketing lies/hype), is biologically a bit of snake oil.

Also, how much does a good soundcard really cost?

Depends on what you need out of a sound card, which is determined by your headphones.

My headphones, for example, need an amplifier. You don't see that on a lot of motherboards, so I did need a sound card. You can get that on a sound card for ~$30, but it is a crapshoot on whether that card has decent support/drivers. I had a shitty card which I later upgraded to a $70 card which works marvelously.

Another thing to consider is the software features that come with a card. Even if a lower end card is capable of X, that does not mean the manufacturer will package a good software suite with it. My upgraded card came with a lot of added software features that were expanded upon from the other card.

If your headphones do not require an amplifier, and you do not get static or garbled sound out of your motherboard, you really don't "need" a sound card if you can get enough volume. Most motherboards even come with an equalizer so you can tweak your sound output so you don't even need it for that.

A sound card will more often come in handy to people who do more advanced tasks such as recording music and such. I am speaking more specifically about general use, movies and gaming with headphones.

That is my two cents anyways. There is entirely too much marketing hype along the lines of used car salesmen when it comes to audio, and way to many people that willingly buy into it same way they buy into the superiority(/s) of consoles and iProducts.