New to the forums and the world of pentesting ( and any real computing for that matter ). As I have seen many times in these forums, we are not here to break laws. So how does a person get this knowledge without breaking laws? Well I guess we must set up a lab to work in. I am looking for some input on setup options for a home lab. I really have no money to spend on more equipment so let me first start with a short list of the hardware that I have:
-2 Dell Desktops (one running XP and one running Ubuntu)
-1 HP Laptop (dual boot with Vista and Ubuntu)
-1 D-Link Wireless N router
-3 Cisco 2500 series routers with current IOS's ( all have CSU/DSU's and I have DCE and DTE cabling)

Now I am really no expert in any particular field of computing or networking, but am slowly learning programming (C, Visual Basic, Perl) and the Cisco IOS as I go. I am fairly new to Linux but have just started to read the tutorials listed in the "If you are new to Back Track or Linux read this thread!" thread. I have become seriously interested in pursuing a career in pentesting/ethical hacking and would like some input from those of you who have some experience in these fields. My questions are as follows:

1. With the hardware that I have, what would be the most realistic setup for me to experiment with?
2. Should I install any other OS's?
3. More of a legal question but: If I set up this lab, would I be breaking any laws if I attempt to exploit this lab from a remote location?
4. Should I connect this lab to the outside world?

Any help you can give would be greatly appreciated.