You'd better use the "ipodpatcher" utility.
It takes literally seconds and, in my opinion, it is much more simple than the Rockbox Utility.
I'm sorry, but this response is a bit short of a thought. ipodpatcher might be "much more simple", but it also does much less. You can't uninstall Rockbox using ipodpatcher, you can only uninstall the bootloader using ipodpatcher. That makes a huge difference. Especially installation is easier using Rockbox Utility as you don't need to worry about several steps that need to be done (and you have nice features like graphically installing themes

)
Of course you're free to prefer ipodpatcher for bootloader installation, but for installation itself Rockbox Utility is the preferred method for the majority of users (and it's also the recommended one). ipodpatcher has advantages if you run into problems with bootloader (un)installation.