I appears that you created your macro in your Personal.xls file, which resides on your hard drive. When you create the macro, you need to select Save Macro In: This Workbook. That way it stays with the .xls file and can be transferred to another computer.
The Personal.xls method is good for macros that you might want to run at any given time, without having to load a specific workbook. But it isn't transportable to another computer (unless you copy and overwrite the Personal.xls file, that doesn't reside where the rest of your .xls files do).