Windows PHP vs Linux PHP

Hi, I asked previously about the differences between the two and the concensus was any differences are in the operating systems themselves and not with PHP. Knowing this, how do I get rid of these errors that keep coming up in Windows, that don't in Linux. One specific one is "Notice: Undefined variable: add in E:\IIS Webs\address.php on line 3" Someone said to turn on register_globals which I have. Another suggestion was to put a @ sign in from of all variables. This is a real pain. Anyone have any other suggestions, or is this basically it? Also, is there anything else that anyone can think of that I may have to look forward to using PHP under Windows? TIA