hm... do you have an install budget in mind?
i take back the alpine power pack suggestion; looks like it's not all it's cracked up to be:
Alpine KTP - 445 - DIYMA.com - Scientific Car Audio - Truth in Sound Quality
i think a decent aftermarket headunit will power okay, but nicer front components will sound a lot better if they're powered well.
any preference as to headunit brand? i'm guessing you're looking for a single-din in order to save weight, yeah?