Free for Personal and non-profit use - they say.
You might prefer THIS though
http://www.workrave.com/screenshots/windows/
Goes at it more from a RSI angle, but it's another break inducer and
it's proper freeware with no ifs and buts - though anyone using it in
a commercial situation really OUGHT to make a decent donation!
It says there's an online store to buy stuff to support it, but I
can't find it?