First, I am going to say that FreedomKJ is
absolutely right, the link he posted has great and correct information..
and I don't want to start a fight, "to each his own."
Now with that said, I've had my HIDs since I first bought the Jeep. (about three years)
This is the link from eBay for the ones that I bought..
http://cgi.ebay.com/ebaymotors/9007-2-Slim-HID-Kit-Lo-HID-Hi-Halogen-6000K-8000K-10K_W0QQcmdZViewItemQQhashZitem414afb43eeQQitemZ280430855150QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessoriesSince our Jeep uses the 9007 bulb, the High and Low filaments are in the same bulb, (unlike other vehicles that use two separate bulbs for HIGH/LOW).
this kits' bulb looks like this

This kit also has a slimmer ballast, which is noticeably smaller. It also has a halogen bulb for use with the brights, it is added mostly to be able to pass inspection if your state requires it. Very easy to install, plug and play, unlike the kits that have HI-xenon and low-Xenon, you want High-halogen and low-xenon, like the one I posted.
Also I had to reverse the wires on the back, because for some reason the low is the halogen, and high is xenon, but that is very simple to do as well.
You also want to get the 6000k rating, that is closer to white, instead of blue, which don't produce sufficient visible light output.
Here are a couple of crappy photos I snapped with my camera phone to show you where I mounted them.
Hopefully you can make them out.


Looking at the photos again, even I can barely see where I mounted the ballasts, lol.
I put them on the two vertical metal supports for the radiator, when you get under the hood hopefully, you'll see what I am talking about.
In the second picture you can see the airbox in the top right corner and intake in the top of the image.
in the image below, it is mounted inside the engine compartment between the headlight and the two silver pipes on the left side.

Good luck.