Well, I have to take the A+ test as part of my new job. It deals with Win95 and ms-dos, with mentions of wireless and usb. My job uses WinXP and soon Vista. So I don't know how useful A+ would be for you.
Most of my computer training was on the job. I do have a Bachelors in computer science, but I haven't used any of the calculus I took snice graduation.
I have looked over the basic computer skills classes available locally, but I am unimpressed.
I believe there are universities with IS/IT degrees, but I haven't attended any.
Sorry, I couldn't be more helpful.