Good choice on the JVC unit. They are reliable and simple to use, although they lack the sound quality of better headunits from the likes of Eclipse, Alpine, etc. I had a very similar model, it did the job. I'd take it over a comparable Sony any day.
As far as speakers go, stay away from all Infinity speakers. They have some of the harshest/brightest treble and midrange of any car speakers on the market, and that's no exaggeration. They also are severely lacking in the midbass department. You can attenuate the s*** out of them, but you will never be able to attenuate all the s*** out of them. From someone who spends their life buying/selling/trading/installing/building car and home audio equipment, you can trust my opinion.
What you should do is set a max price to spend on speakers. Not a "I want a $100 pair of speakers, but I could spend a little more" type of price. Tell me what the extent of your speaker budget is. I also need to know if you plan on modifying the enclosures they reside in, and if you NEED a rear soundstage (which you don't).
But assuming you plan on mocking up adapters for the doors and only want a proper front soundstage, here's some good options:
$100, Vibe Audio Black Air -
http://www.sonicelectronix.com/item_28066_VIBE-Audio-Black-Air-6-V2-BA6-V2.html
Yes, these look cheesy, but if they build their speakers like their amps (which uses Arc Audio design with different components), you can expect great results.
$160, Image Dynamics CTX -
https://www.amazon.com (commissions earned)
These are quite popular amongst those who stray from the "mainstream" brands like JL, Focal, etc. They will also kill any comparably priced speakers from any mainstream brand, which is why they are so popular.
$250, Hybrid Audio Imagine -
http://store.12velectronics.com/products/Imagine-I61%2d2-Component-{47}-Coaxial-Speaker-Set.html
Hybrid is sweeping the nation by snatching up all of the sound quality trophies at the big competitions. These will s*** on any comparably priced speaker set from Hertz or Focal.
$350, Hybrid Audio Unity -
http://store.12velectronics.com/unity-u61-2-2-way-speaker-system/
A step up from the Imagine's
$550, Hybrid Audio Clarus -
http://store.12velectronics.com/products/Clarus-C61%2d2-2%2dway-Speaker-System-.html
If you really want to get serious about your speakers, look no further
Just so you know, I'm not paid to advertise for Hybrid, or any of these brands. I also suggest you look into the speaker offerings from Digital Designs. They don't just win SPL competitions, DD is known for making some killer sound quality equipment as well!
Keep in mind that none of these speakers will mean anything if you don't separately amplify them. For that, I suggest you browse craigslist and ebay for some pre-2000 Sony amps. The reason being is that the current Xplod line has ruined the great reputation that Sony once had for building some of the best sound quality amps at the time (including the XM-2000R). Thus, you can find them for dirt cheap right now. Don't worry about power ratings, focus on everything else.
I know it sounds cliche, but they don't make amps like they used to. Pre-millenium, most companies focused on sound quality and build quality. Nowadays, they focus on power/dollar and Class-D amps. I will always choose an old school amp from the likes of Sony, Zapco, Hifonics, MMats, Phoenix Gold, Eclipse, etc. over any brand new speaker amp. Conversely, unless my focus is pure sound quality, I will choose a newer Class-D sub amp over an old Class A/B amp.
Hope that helps give you some direction! Remember that your end result is 90% installation, 5% equipment, and 5% beer. The installation part includes the size/quality of the wires and the enclosure the speakers/sub are in. If you neglect the installation, you are throwing money away.