First of all, if you get someone's IP, it may change in *-2 hours or less if it is dynamic (and most IPs of users are, unless it's a dedicated server, etc), so it won't do you much good. Second, what exactly do you want to "hack" on the remote computer? Telnet? HTTP Server? FTP? Do you want to ruin their network speed? You probably need a port scanner to see if the target has any open ports and take it from there.
If you want to do a Denial of Service (DoS attack) you need lots of people with high speed connection that will ping the computer, overload its network and force it into reboot (Ping of death).
And you probably want to use some linux distro for hacking, not M$-DOS. Try Whoppix - bootable free linux distribution. But I warn you - it will take you lots of time and Googling to learn how to use it, but after that you will have some basic hacking skills.
