What's a good treatment for bad cramps?

Sometimes when I get my period, I suffer these horrible stomach cramps on the first or second day. I get really constipated, sweaty, and nauseated (although I never throw up), and it feels like my ovaries are going to explode. When that happens, I don't have the energy to do anything except lie down on the floor in front of a roaring fan and moan for the next 45 minutes to an hour (which is about how long my cramps usually last before I'm able to get up and move around again -- and then I usually shiver for several hours because I spent so much time in front of the fan!)

I'm in college and have already missed two days of school because my cramps got so bad. I realize they could last for a lot longer, but dang it, I've got better things to do with my time than writhe on the floor

in the throes of agony from cramps. Pamprin didn't work very well for me. Advil works a little better, but sometimes I still get bad cramps, even when I'm taking it. Likewise, when I'm on my period, I try to drink water frequently to keep from getting too constipated. But that doesn't always work, either.

Does anybody here know of a (relatively inexpensive, safe) medicine that might be more effective at preventing bad cramps than Advil? Are there lifestyle changes (i.e. changes in diet or specific exercises) that can help prevent those cramps? Have any alternative therapies (i.e. acupuncture) or home remedies been known to treat or prevent severe cramps in women?