I've got a '98 EB, but if replacement is anything like your '03, then it is just plain stupid simple. I changed all my door speakers in about 45 min.
I bought thru Crutchfield (I have no ties to them), and they provide all the extras plus instructions.
One note to the wise, be sure to protect the speakers. In my case, the front door speakers were enclosed in a case. I wondered why, then saw that if there were any leaks from the seal on the window, the speakers would be dripped on and trashed. I had purchased just for the heck of it the waterproof foam baffles, not knowing if I would need them....I did, and put them on all speakers. I also installed the "bass blockers" to help prevent distortion, letting the sub handle the lows.
Good Luck!!