Well first, the X2 Pro has a ribbon cable+ adapter (not sure if it comes with the chip, maybe someone here who bought the chip can verify?) that hooks up to the switch's, and it sits externally on the back of yout xbox. You can look at a screenshot of it
here.
The X2 Lite... well,
this is the best picture I can find. Look at the left prong. Notice the black cap is gone? Well, you can install a switch on all 3 of those by removing the cap and soldering one on.
I am not experianced with the matrix at all. I'm not even sure it is pre-flashed. You will have to get a programmer and flash the chip with it. Also, the X2 lite/pro are preflashed but with cromwell bios. Which means you will have to doenload ozxflash and find some hacked bios on the net before you can use the chips.
I'd prefer the x2 lite simply because I haven't much info on the matrix/xodus chip.
Here is a guide for installing a larger HDD.