Start with something that sounds decent. You probably aren't going to get that in "surround sound" on your budget. And forget the .1 (subwoofer). The "subwoofers" that come with Logitech, Creative, Cambridge Soundworks, etc. are a joke. Sure, you can hide that rattling piece of **** somewhere and have little, tiny, cute speakers. And awful sound.
Just get a pair of powered studio monitors. The suggested AudioEngine model is a good start. Check out M-Audio and Behringer, as well. I'm pretty sure Beringer has something in your price range. These speakers all have bigger drivers than the so-called "subwoofers" in the packages with the cute little speakers, so you can dispense with the subwoofer (or add a REAL one if/when you think you need it.)
For surround sound, you will need either a desktop with a card with multiple analog outputs (common for PCs, only gonna work for a Mac if you have a Mac Pro), an external USB interface (adding $50-$100), or USB speakers. Not sure about surround support for USB speakers.
I'd suggest just getting a pair of powered studio monitors, and upgrading to an external USB interface and surrounds if/when you can afford it and feel the need.
Forget any of the "fake" surround solutions. They are generally gimmicks. There is SOME validity, as they make use of SOME of the psycho-acoustic effects that help us locate sounds, but they aren't very convincing.
For example, one way is modeling the effect of the ear lobes on sounds arriving from the rear. The earlobe causes a mid-frequency dip, so a mid-frequency dip will to some degree fool the brain into thinking sounds that arrive from the front are arriving from the rear. You hear the primary sound coming from the front speakers. Then, after a short delay, you hear the "dipped" version coming also from the front speakers. You get some perception that the sound is coming from the rear. I have a pretty high-end version of this on my TV - a $1000 speaker bar from Definitive. Believe me, it really doesn't work. I use real surrounds on my TV, and cut-out the "fake surrounds" in the bar. I only use the built-in surround when viewing from a different room on a swivel, when in the living room I switch over the the real surrounds and there is NO comparison.
Another trick is aiming additional speakers in a single enclosure to bounce off the walls, etc.