I assume you know how to tell Windows you want to use the mouse in your left hand. Control Panel, mouse, etc.
I would recommend you get a copy of TweakUI XP TweakUI XP is a Microsoft PowerToy that gives you access to system settings that are not exposed in the Windows XP default user interface, including mouse settings, Explorer settings, taskbar settings, automatic logon, and more.
There is a set of Windows XP PowerToys (it has TweakUI in it) that you can get from MajorGeeks
Finally, if all else fails, post a query on Major Geeks Support Forum. If they can't help, it probably can't be done.
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