The 4600/4600i makes a poor candidate for upgrading to Windows 7 (or Vista).  Dell DOES NOT support Vista or Windows 7 on this model and thus some hardware devices, especially the audio will not work.  How much memory (RAM) do you have?  You need at least 2GB of RAM for Win 7.   The Microsoft "minimum system requirements" are not real world accurate and can be misleading.  With the "i" model with internal video it most likely does not have the resolution to run the "Vista" Aero video options withing Windows 7.  If you want Windows 7, the best option is to buy a new system that has modern hardware that is compatible with Windows 7.  The 4600i's "old technology" although may be made to marginally work really is not up to modern software needs and hardware and standards.  I know this isn't what you want to hear, but I am being straight and truthful.
Greetings Friends, I had hoped to upgrade to Win 7 from the XP Home I had been happily running for many years on my Dell Dimension 4600i. When I bought the Win 7 program it came with the Install disc and a Dell "Upgrade Assistant" DVD.  The seller attached a slip saying I should not use the latter.     
Cannot Install Windows 7