Here you go:
https://bitcointalk.org/index.php?topic=24268.msg304195#msg304195There are exactly 2^160 possible addresses as long as we keep using RIPE-MD160.
2^160 is 1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976.
You won't be able to generate all those addresses, even if you had the largest botnet on earth and you generated addresses nonstop for dozens of years (did not do the actual calculations tough).