Well what about if you use nmap -v -v -sS -PO -O -p 1-65535 192.168.x.x

[list=1][*]-v verbose[*]-sS SYN stealth (best TCP scan)[*]-PO Dont ping hosts[*]-O OS detection[*]-p ports to scan 1-65535[*]192.168.x.x = host[/list=1]

You can also setup decoy's using the -D option in nmap. Decoy allows you to hide your scan. I say 'the more the merrier'