You've already been given "helpful suggestions"... or at least they've already been posted in this thread.
Here are your choices:
a. forgo syncing your phone with your Mac altogether.
b. buy a newer Mac that supports the version of iTunes that is required to use that phone with it.
c. install Windows via bootcamp or using virtualization and sync with iTunes for Windows.
d. find an alternate method of transferring the information you want to get onto your mac from your phone (photo stream, email your photos, etc.)
e. sell your iPhone and go buy something else, which you will not be able to sync with your Mac either...
What you do is completely up to you. The options have been made clear. Continuing to whine about it isn't going to change anything.