Logitech just throw in a car sub woofer and every one jumps for joy that the quality is so fantastic. All it is, is a boomy bass, with no mids at all. Plus the subwoofer has a terrible transient response. The satellites just are one way speakers, so again, they cant produce proper mids. And the amp is ancient. You need to have at least a three way system. I would rather get a sansui 5.1 system than that. (Note im only talking about the z5500 here)
For R600 to R1700, I would get decent headphones, and save up for speakers. R1700 can get you a pair of sennheiser hd555's.