what OS are you running? if you are running a win32 OS try N-Stealth it is better used to find insecure programming, buffor overflows, and directorys open to the net. Its pretty fast not the fastest, Im not sure if anyone above has mensioned Retina.. not bad but it doesnt find all that much compared to a few others, the best i have used and swear by is prolly nessus. You can run nessus on a win32 although you will need to download the win32 version: just goto google and search for winnessus you should find plenty. And if you dont like none of the above try webtrends Network scanner- its got a nice gui and reports well.. umm cant think of any at the moment but there are hundreds out there so yeah best place to look is prolly astalavista or neworder.box.sk they have got a great listing of them, cant forget to mension www.packetstormsecurity.com <---- biggest tool listing
hope i helped =)