There are decks available that put out 200 Watts. That should be more than sufficient for your needs.

A trip to Circuit City (or Tweeter or your fav electronics store) should be on your agenda before you purchase anything else. They should have a whole bank of car audio stuff on the wall. You can listen to different ones then pick the one you like the look/sound of in your price range. Don't make it more difficult than it is. You got good speakers, why not just install them with the stock stereo. If you don't like the sound, then buy a new stereo. If you don't like the sound, get an amp & subs.

I'm still running stock radio & speakers. When the speakers blow, I'll upgrade. When the CD changer dies, I'll upgrade.

You don't need to impress anyone but yourself. Don't put anything in that is more than you need/want.