Does your add-in target Office 2010? (you say your test machine has Office 2010 installed…). If so, then the workarounds in Misha’s blog are no longer required. Please see http://blogs.msdn.com/b/vsto/archive/2010/03/08/deploying-your-vsto-add-ins-to-all-users-saurabh-bhatia.aspx.
If you need to target Office 2007, the only supported approach is to install the Office 2007 hotfix, as mentioned in the blog post I referred to.
If neither of these options are possible for you and you want to try to use the unsupported approach described in Misha’s blog, someone here might be able to help you if you can provide more details about what you mean by “Windows 7 seems to have changed everything”. Are there particular instructions in Misha’s blog entries that don’t work on Windows 7, are you getting particular errors, etc.? One idea: since you’re running a 64-bit version of Windows 7, make sure you take a look at the reader comments about 64-bit at the bottom of http://blogs.msdn.com/b/mshneer/archive/2007/09/04/deploying-your-vsto-add-in-to-all-users-part-i.aspx.