http://articles.moneycentral.msn.com/CollegeAndFamily/SavingForCollege/6ReasonsNotToSaveForKids.aspx
I financed 100% (with a little help from my parents) for 8 years of schooling. The biggest part of this that I think deserves merit is this:
Students should invest in their own education
Every year a number of freshmen trek off to college on their parents' hard-saved money, only to spend more time the first few semesters partying than studying. Would they crack the books more if they were paying the bill? Even the most responsible kids seem to do better in college when they help pay for it.
Helping your kids through college is wonderful and demonstrates that you value their education. Give enough to help, however, not enough to lessen their investment in the outcome.