OK Greg, this has gone far enough....beat me too it again and I'll never log off. 
Given what you listed (IMO) Clarion would be the better purchase...their amps are electrically equivalent to the KAR model of Arc Audio - a most definitely higher-end audio company.
that said, I agree 110% with Greg on components, subs and an amp - most bang for the audio buck. IMO, rear deck speakers are great for a 4-door car and "normal" listening levels - so the folks in the back can hear the music without it being TOO LOUD for the folks up front.
edit: I gave up the audio forum mentioned, too much noise in with the good stuff, now I usually go here:
http://www.carsound.com/cgi-bin/UBB_CGI/ultimatebb.cgi
you can frequently find posts at this site by national IASCA winners, i.e., Scott Baille, et al.