For that amount of scratch, you can have both. I managed to pick up my Logitech Z-5500s - as mentioned, a full 5.1 system, for about $140 on sale. Look around and you can find sales for these.
That still leaves you over $150 with which to buy studio quality headphones. Some people like Grado, some people like AKG, some people like M-audio. All good picks.
If you don't like 5.1, I hear that the Swan M40 and M-audio AV40s are both good 2.0 sets. And you can definitely afford them.