I would replace the speakers. I have noticed a trend in the Audio magazines which have recommended systems, they often have $1000 - $2000 integrated amps driving speakers that cost $3000 - $5000. The speakers (and how they integrate into your room) are still the weakest link in the stereo chain. Maybe this says something about the quality of todays amplifiers too but, I stand by my recommendation.
I would change the wire last.
I would change the wire last.