hey guys, new member here, don't really know a whole lot about audio. but i love my music and i've decided i might as well spend some money and put together a decent quality system. i'm looking for a system to hook up to my laptop. right now i have a $50 set of logitech speakers + sub that came with my computer. its not terrible, but its not all that loud and the sub is quite embarrassing. i'm not sure quite which direction to go right now. i'm currently at college and at home my dad has some older polk audio speakers cabinets which are missing the speakers. I'm not sure on which model, he'll get back to me on that. He says they have crossovers and the tweeters should still be fine, they're just missing the speakers. so one option would be to buy new speakers for those and then buy a subwoofer to go along with them. I found a sony saw2500 while searching online and that seems to be decent quality in a price range that i'm looking for. Now, will that sub power the speakers, or will i need another amp to power the speakers?
another option would obviously be to just buy a better set of computer speakers. which option would be best for me? realistically i'm not looking to spend over $200. being at college, space is a bit of a concern, but really i shouldn't have any problems fitting speakers somewhere. i just don't have room for a huge subwoofer.

thanks for any/all help.