Now I wish I'd looked more into sound cards, instead of just equipment.
I'm going to assume when you say "equipment," you mean like speakers or headphones and whatnot.
If you're into music making, then you're going to have to buy whatever suits your needs, I can't tell you what to get there. I do know that it's best to have a sound card that supports 5.1 channel (5 speakers 1 subwoofer) speakers, subwoofers are bass units. For a good subwoofer, you want to have at least (and this suits my needs fine, but that's just me, again) a 30-watt, 9 inch subwoofer. This is enough to shake floors without distortion. (:D)
Speakers, I don't look into too much, but size does matter. Material does, too, due to acoustics, reverberation, etc. Basically, the bigger the better. I've never had "good" small speakers. But, building them is an option. Building a speaker is like taking a box (for acoustics) and placing the speaker unit inside of the box, among other things (I've never built a speaker, I trust companies. :P)
For sound cards? You're going to want it to at least deliver 190000 Hz, at 5.1 channel sound. (surround)
But, that's for my case. I doubt you're into in-depth audio design. 41000Hz works fine for most people, but that's usually if you aren't into the kind of stuff I am. (that's like, CD quality as opposed to studio quality)
Then there's the matter of headphones and possibly microphones... Microphones? I don't record live/sing, so don't ask me on this one. Headphones are the same deal as speakers, if I were to buy headphones at a great price for great quality, I'd get Sennheiser HD-280Pro headphones. They have 3 models, I think "Pro" is the best deal for the best price. More 'bang for your buck.' They're around $170 if you can get them on sale. ;3
To sum it up, sound cards and speakers work like monitors and computers. You want options, therefore you want high quality stuff. More hz=higher quality, but for speakers, you'd have to look up an equation to find quality, especially for bass. I have a 12-inch, 200 watt subwoofer which a lot of people think is a bit much, but hey, it works for me. Your sound card should also have at least 2 audio inputs/outputs. (Mic is input, speaker is output)
Then again, there's google.
