Dorm room? 5.1 speakers? Let me tell you why I think you are much better getting a 2.1, or even 2.0, setup.
1. It's unlikely you will be able to place the speakers in a "surround-sound" position to get the right sound imaging.
2. You get what you pay for. A $70 5.1 set of speakers will sound abysmal. Those tiny satellite speakers are going to have very feeble midrange, and the subwoofer is not going to be much use. And they are big and clunky and take up a lot of room.
3. Do you actually have any content that is 5.1-compatible? You'll need speakers that can connect via toslink optical or USB-audio to get 5.1 anyway, the standard analogue audio jack on any computer is only 2.0 stereo (but it's a combination analogue/toslink optical, so you can use a toslink cable to get that 5.1)
I take it that being in a dorm room, there's lots of other people around. So the low bass of what they call a "subwoofer" is going to travel through the walls and piss people off pretty quickly. I suggest you buy a good pair of headphones. They will sound much better computer speakers. Alternatively, you could get some
Audioengine A2 speakers - they have a good reputation. They're basically bookshelf speakers with built-in amplifiers, and give you a good notch above your standard tinny 5.1 system with tweeter-sized satellites and a boomy, imprecise woofer that leaves out the midrange.
But if you really want to crank up the volume without annoying people, and enjoy amazing sound for a great price, headphones are the way to go. I'd tell you to buy the
Denon AH-D2000's, but maybe that's because I own a pair and absolutely love them! But perhaps given the $80 speakers you linked me to, both of my suggestions are way over your budget.
Denon make a lower-down model, the
AH-D1000 which apparently sound quite similar to their bigger brother. The Denon headphone range is absolutely top-notch, with a surprisingly open sound for closed-type headphones, and a slightly warm sound with solid, punchy bass and clean highs.
Basically, the message here, is you get what you pay for. You aren't going to get a good PC speaker setup for $80, it will just sound horrible (to my audiophile-tuned ears anyway
). You'll need to stretch your budget a little higher to a
good 2.0 setup or some decent headphones if you want good sound. If $80 is all you can spend, go for the
Logitech Z-2300 if you want speakers, or a good pair of Sennheisers or something for headphones.
Hope this helps.
Edit- with an el cheapo pair of speakers, you aren't going to gain anything with an external sound card.
Any set of speakers that can connect to the 3.5mm audio output on your Macbook will work. With headphones you'll need to be wary and ask if they will work with a computer - some of them are very insensitive and require a dedicated headphone amplifier (though this requirement is almost always restricted to expensive headphones).
