Oh I guess I should mention that I'm a computer programmer and am on my computer way more than most people so I really am probably more lenient on his computer time than most.
LOL - this is how it is at our house. Both DH and I have backgrounds as software engineers and it would feel totally disingenuous to not allow our kids to explore technology.
That being said, we do monitor recreational computer or wii time. DS gets 20-30 minutes a day. Since we homeschool, he uses the computer a lot during the day. I have a kid that would definitely play Wii day and night if allowed to do so. DD5 hasn't really needed a timer yet and the vast majority of computer things she does are educational anyway. She gets off on her own generally.