Erm you havent given any info about what OS you want to use it on or anything. If you want a decent scanner for Windows something like Superscan would probably do the trick. On Linux Nmap is always a favourite and you can even got a GUI for it now if you don't like using the command line.
I second what UKnetSec says - SuperScan for Windows and nmap for Linux. nmap is also a stealth scanner which makes it far more effective than something like SuperScan. You could also try the Windows port of nmap.
Well, if links are going to make your life a whole lot easier