I've had a couple different sets hooked up to my Mac over the past few years.
-1st I had the Bose Companion 2 (original version) found they were too bassy and lacked a mid range.
-Had a Logitech 5.1 System Z5300 maybe? They were okay, very flat sounding. Didn't have too much depth to the sound. Not enough treble, and too much bass.
-Had a set of Klipsch 2.1 ProMedia's. Almost similar to the Logitechs as far as sound. Was fine for some music, but they got too loud. When they got loud the sound got very distorted. I found them to not be as well balanced as their 2.0 counterparts. If you simply don't care about anything but being really really loud, these are okay for you.
-Finally settled with a set of Klipsch 2.0 ProMedia's. I find that they have the best mix of everything. Great bass, amazing mids and highs, and all in a compact 2.0 footprint (no subwoofer). I found the price to be very good, they were only $100. I've had mine about 18 months now and they're great, no issues what so ever.
Also, I mainly listen to rock and some indie/acoustic folk, if that helps. I think these speakers will be all around great though.
Edit: Just did some quick research and apparently a lot of places aren't carrying the ones I reccomended to you anymore. Apple used to, but they're not anymore. I found them at B&H
http://www.bhphotovideo.com/bnh/controller/home?O=productList&Q=396297&A=buyUsed
There's apparently a replacement/updated model, but as I haven't used them I can't comment on them.