If you are going for a very good system, I'd recommend component speakers for the doors. I recommend the 6500's from Elemental Designs. You can get them at a group by prices by ordering them through this page -
link. Compare them to the lower 6000 model price which isn't available through that link. If that's too much, there are some b-stock CDT components sold through CDT's ebay store.
Later on, amps from ED are a good choice. Their subs are a good value but not the best. I like ones from TC Sounds or Soundsplinter (built by TC Sounds).
-Robert