I just got a letter in the mail this week from Ford recommending that I schedule my 100,000 preventative maintenance with them. I have 97,000 miles and am wondering how much Ford dealers typically charge for this service, what it includes, and whether or not fellow X drivers that have used this service would recommend it for someone who is not very mechanically inclined to the do the preventative maintenance himself. Advice?

I've never rec'd that letter, but I just rolled over the 100k mark.

Basicaly, if I got off my dead arse, I would change the oil (easy), front/rear differential fliuid (rear is easy), plugs & wires (easy)

Depending how much maintainance you get done to your vehicle on any kind of a regular schedule you might want to also:
change the coolant(fairly easy)
transmission fulid flush
t-case fluid change

Other than that if you are noticeing any problems have them checked as well