You are not anonymous, its just a matter of how hard somebody has to try to find you, and if its worth the effort.
Finding your ISP is easy, getting from there to you is harder.
In the good old days, there were free servers that hid you behind them, but again once you have access to the server the cloak has gone.
The easisest way to make life easier when trying to find you is to send you a virus, or spyware, which sits there and reports back everything you do.
There are levels of everyting, your firewalls, spam filters, virus scanners will keep out the script kiddes, but not the talanted attacker determined to find you.
Rick