Is there any kind of software I can download in order to compile and run my C unix programming code on?

I realize I need to download an OS. I have windows xp professional. What can I download so that I can compile and run my unix C programs on?

I have microsoft virtual pc and I got it to work on my desktop computer but it wont work on my laptop for some reason. I do most of my work on my laptop so I need a solution fast.

So just to make things clear, I just need something I can compile and run my unix C programs on. Do I need a unix/linux OS? Sorry, I'm a beginner so I don't know the difference. I just need something that can read all the the standard libraries I use in my programs like:

#include <stdio.h>
#include <stdlib.h>
#include <dirent.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <signal.h>

Thanks.