I just installed ubuntu 12.04 on my old imac7,1.
The first thing I did was install refit from OSX. After that, I installed ubuntu from a liveCD and all went apparently fine.
The problem is that GRUB shows up instead of refit and there's no way to boot OSX because when I choose OSX from the grub menu nothing occurs.
I have found this topic that seems to talk about this problem but it's my first ubuntu installation on a mac computer and I don't want to mess the things up.
And also this is the answer given from iamwpj, that seems to be my solution but I don't know how to do it.
I actually figured this out. The easiest way in any situation where GRUB overwrites rEFIt is to hit C when the GRUB screen loads. This will bring up the grub command line. Typing exit here will exit GRUB and show you rEFIt. From here a boot into OSX will allow you to uninstall GRUB and install rEFInd.
Should I uninstall GRUB from ubuntu? And, after that, will refit show up?