Set process name

So i need a bit of help finding some code.
I'm looking for a code that can change a process name (the one you see in task manager), either while its running or before it starts - it doesn't matter. Bonus if you can show me how to hide the process from all programs.
code in: C++, C#, or VB.net appreciated. Anything else is fine, but it'll be a hassle.

>>4
I looked up the function you gave me, but it doesn't work on current systems
so I'll have to resort to another method.

I think what I'll do it just have my app copy a program byte for byte to a temp location under a different name so it can start with a different process name.

unless anyone has a better idea?