what bod said..you can also manually detect it. Go options>games>click not installed games so the menu drops down and scroll till fallout new vegas, set automatically detect and click apply at bottom
It's because New Vegas is bound to steam, so xfire tries to detect the game @ steam.exe -app:newvegas...etc.pp. You have a cracked version which doesnt connect to steam, so there is nothing to detect. No chance m8...