[Faner]

http://www.youtube.com/watch?v=n9Ouc5Wsr08

Good video about arp poisoning: first explains what exactly is and then shows it in practice.

By the way, some time ago I was trying this on bt5. Both computers were connected via cable, and on the router there were only those 2 pc -> mine and victim's (also mine).
Whenever I tried to poison arp, it showed "Arp poisoning successfull.", but when I checked it with plugin "Check_poison" or smth like that, it returns "No arp poison were found."
And of course sniffing also wasn't successful, only thing I got were a bunch of errors. Any idea why it happened?

you don't have any gateway or router connected in physical machine.
use this in vmware and use NAT network.. it have virtual router..

I am pretty sure I have a router, after all it hangs on my wall.
And about gateway:

Windows IP Configuration
Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 192.168.1.101
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.1