how can i make NBC website think i am from usa while i am from uk as i want to watch some programs??

You can't. They know your IP address and there is a web page you can visit that will show you the location of each public IP address being used on the Internet.

Hackers can -

but they are smarter then us mere mortals.

Go through a proxy server that's in the USA (go to your browser's options to set it up) and it will give you an American IP address. Go to http://www.echolink.org/proxylist.asp and scroll down to find a USA one and use that. The problem with these is that it has to re-route all your Internet traffic to and from America so it slows your connection down a bit. Some of them are still fast enough to watch online video, but some aren't so you might have to try a few different ones.

Maybe you can try this: http://satellite-tv-on-computer.info/

they say:

You Can Get over 3000 STATIONS on your PC. You don’t need a satellite dish, receiver, or any cable or satellite service! All you need is an internet connection and a computer. Watch all these channels anywhere in the world. More than 1 million users are already enjoying the incredible variety.

No idea, but it is only certain shows that are blocked, maybe because they are being shown on UK TV now or soon and they don't want you to get a sneak look before it's broadcast here?

Sorry friend - it's all done by your ISP address - linked to your phone line. Nothing that can be done (this side of the law!!).