The Windows %path% environment variable should by default consist of this:
%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem
If all that has been nuked by a Java install (this is known to happen sometimes, by the way) you have problems, as has been noted. Typically, this is caused by an installer over-writing the path variable when it should be appending to it. I believe this can happen with systems where the previous path string was over a certain number of characters (some installers barf at 512, others at 2048)