OK for my son to go back to school after flu?

My 5-year-old son is recovering from the flu. He came down sick Wednesday night and was tested at the doctor's office on Friday. He did have the flu, specifically Type A. We started the Tamiflu Friday night and by Saturday his temp was down to normal and he's had no more fever since. He is acting like he feels fine, and was actually pretty active today.

The doctor's office said he had to be fever-free for 24 hours. I know that flu can pretty well wipe you out for quite a while after the fever goes down, but he seems to be back to his normal, active, little-boy self. He doesn't have enough absences for one more to be a problem, and academically it won't hurt him to miss another day, as he's a bit ahead of most of his class. I plan to check on him during the night and make sure all his activity today doesn't bring his fever back up.

Assuming his fever doesn't come back up, should I keep him home tomorrow? Nothing short of Benadryl will keep him resting at home during the day. I guess what I really need to know is if he could still possibly be contagious, or if he REALLY needs more enforced rest. He's better a lot faster than the doctor thought he would be, and if I wait to call the doctor tomorrow, and the doctor gives the go-ahead, he'll be at least an hour late.

Experienced parents or health professionals, what do you think? Thanks!