I beg to differ... that's what your firewall is for.
The only reason random IP's would have any reason to connect to your machine via the web (HTTP port 80) is if you're actively doing something that would warrant more than just a firewall.
In most (read, not all) cases, normal web surfing does not constitute that. Filesharing and torrenting does. It actively opens a port to your PC so you can stream file chunks to other people. Thus, opening your PC to whomever connects to that port.
If you don't open the port to the world, you have no problems. To each their own I guess.
True, torrenting is overrated though, I never use it.