my 2cents

if you go decide to go with an pioneer head unit, i'd suggest the 8600 or the premiere 860. they both have time alignment so later on when you get more into your stereo you'll be set. i never tired the eclipse head units but i've heard great things about their mid to high level head unit.

i use the infinity components in my car, they are great for what they cost but lack in the mid ranges i think. the infinity perfect components are suppose to have a bit more bite to the mid range. i've actually made the kenwood excelon components sound nice at work before. the alpine type r's and type x's are also good too.

as far as subs go, the jl w7's are just hella expensive and i would get a adire shiva for half the price and i heard they're very close to w7's. also the alpine type r's are a great bang for the buck. the infinity perfects are great i've put them in a few cars and they're strictly nice sq subs. rockfords i just don't like, i'm not sure if it was i use to install all their stuff when i was at best buy or not but i think they're over rated the punch stage 3's are nice but kinda needs alot of power and space.

as far as 4 channels i would definately get into the polk momo amp, it has a great s/n and as well as can be setting to be an active crossover. the new jl and alpine amps are alwasys a great choice.

i would say the importants parts to look at is the head unit and amps. since you can use alright speakers and tweak them with the amp or headunit to make them sound better.