Some good advice in the last half dozen posts! Based on my own experience, I would not recommend a suspension seat post, so it's interesting to hear them recommended.

Reynolds, you can certainly make that Free Spirit ride pretty well and give you a pretty good idea what riding an old road bike is like. It will be bumpy if you just sit there, but if you put your butt in gear and actually ride the thing like a sports car, you'll forget all about the bumps.

A better bike would probably be better, I can't deny that, but this one is probably fine for now. I vote, keep it and ride it and learn to maintaiin it yourself. Learn enough about this one that when something good turns up on Craigslist you know enough to grab it before its gone.