What you didn't say was what the software was going to do. If it was true administrator software, then it can require administration privileges. If it's for a specific use and your client approves, it can require administration privileges (ask the client before assuming it's OK). If it's something a normal user might use, and will see use outside an enterprise that has specifically approved this,you need to find a way to make it usable by less privileged accounts, and if that includes not making changes to the system registry that's what you'll have to do.
Windows Vista introduced UAC, which was designed to make software like yours, which requires administrator privileges, awkward to use. This was for a reason: allowing people in general to run as administrator at all times is a big security issue. More and more enterprises are passing out computers without admin privileges, so your software will be usable on fewer and fewer corporate systems.
If this is some sort of home/personal software, requiring admin privileges is going to make users on Vista and 7 less happy with your software, and is going to perpetuate the global security issue of hordes of individual users, with no computer savvy, being on the net logged in as administrator.
Unless you're in some sort of niche, this is not a user problem (and, if it was, do you really want to be causing your users problems?). It's a developer problem.