Since this is for listening to compressed audio files the bit rate you rip them at factors in. For anything under 192kbps the files themselves aren't resolved enough to really worry about the most detailed speakers. Great speakers are definitely the best place to put your money, but they will ultimately reveal the deficiencies of your source. I don't think you need to worry about a receiver/amp but you can get a Yamaha for under $200 (http://www.jr.com/JRProductPage.process?Product=4031471) and a Pioneer for less.

If you want some punchy speakers, fair detail, with decent bass for a small room, I like Paradigm Mini Monitors. Price around $350 I think. Start with these and then upgrade the rest as money permits. These are good enough to make a real positive impression. The can rock, they are quick and IMO very good with edgy, alternative music. The stuff you listed is not too very bass heavy. You’ll probably not miss a subwoofer. And, the Mini Mons are not so detailed that you will immediately hate listening to compressed files.