Head-Fi is great, but be careful. It's full of a bunch of subjective nonsense based on hype, which can cloud some of the truly good information.
I would recommend investing in a nice DAC and amp for headphones. There are several sound cards with integrated headphone amps that act as a nice budget DAC + amp. Many nicer headphones benefit from the additional power, and the signal itself is of higher quality as well (less noise, for example). Creative had a decent USB DAC + amp (X-Fi HD, the newest model). It has a built-in headphone amp as well. Surprisingly solid device for the money.
If you don't have a sound card with a dedicated headphone amp, the 3.5mm jack is likely a line-out designed for computer speakers or stereo receivers. Not only do they not always provide the best signal for headphones, if you will, but they also sometimes simply aren't a good match up at all (high output impedance, for example). This is not always the case, but it can happen.
As for headphones in the price range (not including cost of DAC and/or amp):
1. Audio Technica ATH-M50 - These are nice, budget headphones. They have a fairly neutral response overall, tilted towards a bit of additional bass and a few rough spots in the mids and treble.
2. Sennheiser HD558 or HD598 - Get the HD598 if you can afford it. These are open headphones. They had a large soundstage and a very natural, effortless, slightly warm sound overall. Fairly balanced, if a tiny bit lean in the sub-bass region. While not as bass-heavy as the ATH-M50, they are smoother and more even sounding overall.
3. Brainwavz HM5 - Decent headphones for the price. Tilted more towards the neutral side. I prefer the ATH-M50s and HD598s to these, but many people really like them.
4. Mr. Speakers Mad Dog - This is a heavily modified version of the Fostex T50RP headphones. The T50RP is extremely popular due to its extreme potentials after being modded. It's a planar magnetic headphone, so the sound decays very quickly and cleanly compared to most other headphones. Simply put, when given an impulse, the driver that creates the sound will stop moving faster than it would on a "standard" headphone. The T50RP is smooth and clean sounding in general compared to most headphones.
Anyway, the Mad Dog is a highly modified T50RP. It takes a LOT of effort to mod and tune these properly, which the creator of the Mad Dog has taken the time to do. You can even find measurements for the headphone on the website. They are comparable to the HD650 or the LCD-2, the latter of which costs close to $1,000. They have a very similar sound signature at a much lower price ($250). I have my own modded T50RP (a different, more expensive variant from another person), and they are absolutely incredible. If you want the best, I'd go this route.
With these, you basically need a decent DAC and amp. You can find sound cards or external USB sound cards with nice, dedicated headphone amps for $100 or less. You might have to go used or refurbished. I liked my Creative X-FI HD USB device, and I'm currently using an Auzentech Bravura sound card (refurbished for under $100).
5. Denon AH-D2000. I believe these are technically discontinued, so they may be hard to find now or in the future. These are a fairly bass heavy can (extends very deep). They have a somewhat recessed midrange and slightly bright, occasionally sibilant treble. I thought they were fun to listen to, and they're quite popular. They sound surprisingly open for being closed headphones.
With these, the Mad Dog (or any T50RP variant) benefits most from a nice DAC and amp. The HD598/558 is up next. The rest do fairly well from standard devices, but nicer gear won't hurt them!
I'll add more headphones if I can think of them. Just be careful when researching! Many people are extremely biased and subjective about headphones, so it's good to back your research with measurements, data, and expert opinions (which, even then...occasionally scary and untrustworthy). Feel free to ask me any questions.
Edit: Stereo headphones would be best, in my opinion. I really don't like the virtual surround stuff through software either. If you have a nice, somewhat accurate pair of headphones, the soundstage and imaging should be at the very worst adequate for almost any listening situation. The HD598 on its own, for example, sometimes fooled my ears into thinking they were listening to actual speakers. Just my opinion!
Be careful about Beyerdynamic headphones. Their older models weren't too bad, but their new headphones are generally either bad or bad and terribly priced. The DT 770, 880, and 990 all have rather pronounced treble. The DT 770 has that along with elevated bass. The nice thing is that these headphones respond well to EQ. It's cool if someone likes how they sound, but I think there are better options for the price.