I have used several... I like Cybersitter the best because it sends me an email every day that includes the entire chat sessions for all major chats, all pages visited and those that were blocked, etc. I can shut down chat, or internet, etc. and there are 36 topic filters for blocking or warning so you can, say give access to Sex edcuation stuff but not adult explicit topics, etc.
And, even if someone has or somehow manages to get admin rights on the computer, the admin feature of Cybersitter is unique to the program.
Kids can manage to get access... I gave my 15 year old admin authority in WinXP Pro. He tried to create an ID that would let him on the internet during the day when no one was home or exempt from the restrictions but, he did not have access to the admin panel for CyberSitter so he still could not add the new ID to the exempt list (selected users in the exempt list...). But, what he did do was to change an adult ID password (friend that rarely useshis id on that laptop). But the chat sessions and the pages visited were still stored in the log and emailed to me so I knew immediately the kid was logging on and using the ID since friend had not used the laptop in a month.
I also used ContentProctect at one point which is very nice too... but you have to go to the website to look at the info on chats, etc. Its a really nice interface and its nice feature is that can have "user ids" so each person has their own individual setting.
Cyberpatrol is another option...
I still like Cybersitter since I get the email daily and can breeze through the log. Kids didn't know their actual chats were being recorded... son had done some dangerous things on the internet including putting his real telephone number out there and a 28 year old man was trying to convince him to give him his address so the guy could come over from Cali and wait until adults were not home....
So if you think you DONT need a monitoring program, think again!