laptop??
well...u never get the clean sound like playing directly from a headunit...

if i were u...id look into eclipse headunits..
their cd/dvd players are excellent..<my friend has one>
i think they have digital/dts decoders built in...so you wouldnt need a seperate decoder...<which save u a few hundred bucks>
also...do look into zapco lines of eqs and crossovers...
theyre high quality of course do a great job for ur sound needs..

for speakers and amps...
set a goal for ur system...and find the right components that meet up to ur specs...