I need some stereo advice/recommendations.

After learning here of the craptacular nature of the WRX stereo "upgrade," I opted to get the basic 6-disc in-dash changer and later upgrade on my own. I'm not a sound freak outside the home, but I would like this baby to sound punchier and clearer.

However, I don't really want to break the bank on an upgrade. Ideally, I'd like to keep the current deck and just improve the amp and speakers. What are your recommendations for speakers--front and back and possible subwoofer? What about amp and amp placement?

Is this even a good idea? If I'm not upgrading the deck, should I even bother with the rest? I don't want to spend more than a grand, and preferably much less--say $500.