As has been covered many times in many threads, the current most popular modchips are the wiikey2 and the D2Pro. Both of them support all wii chipsets, are updatable via DVD and have relatively few points to solder on the board.
There should be a serial # checker to see which chip you have in yours.
I was holding off til all the kids were done playing with it (christmas) before I cracked it open,LOL!
2 great tutorials on that site when you scroll down.
All in all,pretty easy and they do use some very,very small screws in it. No soldering on my drive!!!!!
You'll need a Triwing screwdriver,very small phillips screwdriver,and a magnetic screwdriver. Ebay has the triwing screwdrivers for a couple clams.It'll take 2-3 weeks to get the clip-which goes from Australia-hongkong-then here to the USA.
I've tested 3 diffent backups so far and they play perfect.