HSTuners - MIGHT be building my system... suggestions comments

I used to know lots about stereos but not so much anymore...

I just ordered this head unit:

http://sm.crutchfield.com/S-iMtsrXji...0&I=158CDXM881

Anyone know how good the ipod interface is with that optional Connector Thingy

http://sm.crutchfield.com/S-iMtsrXji...asp?i=634MSC02

Now I'm thinking of getting new speakers and amp too... I'm not sure though.

Right now I have:
Old sony tape deck headunit.

JBL GT400 Amp (it's 75or100x4 or 200x2)
Some junk woofer in some generic factory sealed box.

Door speakers are Pioneer components right now I have old OLD infinity Kappa Components sitting around.

That's it.

So now I"m thinking the above headunit.

Maybe the JL Audio E6450

http://carsound.com/articles/publish/article_268.shtml

And the infinity perfect component speakers for the doors and maybe the rear deck.

Then for the sub I"m not sure whether I should get the infinity subwoofer to match the doors or what.

Any suggestions/experience would be appreciatted greatly.