GCC in the Windows distribution of GHC

The Windows distribution of GHC includes GCC. Some header files (such as iostream, algorithm, and so forth), however, are missing (at least I was not able to find them). I could, of course, download the correct version of GCC (this must be version 3.2.3 for GHC 6.4), and put the header files where GCC can find them. I only wonder if this is the right thing to do. Were the header files omitted just to make the distribution smaller, or for some other reason? Cheers, Cyril