Hello, I need to share a macmini/notebook for multiple vesrions of Mac (10.3,10.4,10.5). Right now I format the disk and then reinstall the reuired Mac version. But it is very tedious job. Would somebody suggest some good method to do this? I found that once you have upgraded the Mac, you can't downgrade it. To do it, you need to format and reinstall. Any suggestion(ASAP) would be most welcome.