CMACK,
Probiotics do seem to help both people with IBD and IBS. Probiotics is basically a fancy name for 'good gut bacteria.' As you probably know your gut has both good and bad bacteria in it and it needs to have both to function properly. However, when having diarrhea that good/bad bacteria can get off balance and usually the bad bacteria begins to dominate and cause more gut problems. So, by taking a probiotic you are putting good bacteria back into your gut and helping to set things back on track.
In my opinion, and the opinion of my GI, the best probiotics are 1. refrigerated, to keep the cultures alive; 2. have at the very least 3 billion active cultures; and, 3. have different strains of bacteria like bifidus, lactobacillus, and, acidophilus.
A health food store is your best bet for these types of probiotics. But you might also find them at Whole Foods or Wild Oats type stores as well.
The best part is, probiotics can't hurt they can only help.
Good luck,
Elizabeth