Linux Users

GCC is GNU Compiler Collection.
To install it in Windows XP

Step 1. Download the Codeblocks with the mingw From the folowing link
             Code::Blocks link
Step 2. After downloading and installing the code blocks
             goto directory C:\Program Files\CodeBlocks\MinGW\bin
                to check the contents.
         
Step 3. Copy the Address bar and move to Desktop
              Now,    Right Click on the My Computer > properties > Advanced
   Step 4. Click on Environment Variables and look for the path and click on path,then Edit it.
                               
Step 5. Important one
               leave the rest content of address bar untouched and add a Semicolon and then the Copy the content of address bar
                 ;C:\Program Files\CodeBlocks\MinGW\bin
         eg: %SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;C:\Program Files\CodeBlocks\MinGW\bin

Note that : there is no semicolon at the last address.
Same Way you can add any Command folder address to this path, if you want to use the same commands in XP's command prompt.

Now, Just Click OK and Open Command Prompt.
   Type the folowing in your source Code :

            /* Program to print Hello ! World */
               int main()
              {
               }

Then Save it and Compile it using ( for c language code) :  gcc hello.c -o hello       

if you are compiling the C++ code then  : g++ hello.cc -o hello 
Note that : .cc is the extension for C++ code.