After using these expensive alternatives on expensive OSs, I finally just changed to (yes believe it not) high-tech NetNanny. It works and it monitors everything.
I have a fine line between people's having fun looking up Yahoo for a second and being on eBay for an hour.
An alternative to netnanny is SpecterPro. This works either for employees or your teenagers.
http://www.spectorsoft.com/products/SpectorPro_Windows/"Awarded PC Magazine Editors' Choice
Spector Pro has been awarded PC Magazine Editors' Choice TWICE as the best Internet monitoring software for recording computer activity. PC Magazine reviewers stated, "Spector Pro offers the most powerful and complete assortment of monitoring and reporting tools."