What's the best free compiler that will compile code for Windows under under Windows XP?

MingW (based on gcc of *nix fame) is supposed to be quite good, though I haven't used it much myself.

http://www.mingw.org/

Is it possible to optimize software for my specific processor/setup with MingW? I looked at the cmd line options for the compiler and don't see anything...

And what program do I need access CVS (Windows)?

I'm not sure. Since it's based on gcc (3.2 I think atm) it should be possible to optimize for specific architectures both normally and via vectorization, but I don't know how you would do it.

cvs.exe works fine for me You should be able to find it via google..

Oh yes, there are lots of optimisations in MingW. I used it to compile oggenc with 3Dnow! and SSE for Athlons and it seemed to compare quite well with with ICL.

do a:

gcc -v --help > gcchelp.txt

Then you have a list of all the possible command-line options for it in your gcchelp.txt file.

For an example of the command-line switches, have a look at http://www.geocities.com/steve8988/#how