@Patricio
The file is /boot/grub/menu.lst
I think during the installation of a new kernel, the post install scripts executed by dpkg are updating grub and its configuration files. So you should have nothing to do. But I would still recommend you to back-up at least the /boot/grub/menu.lst before installing the new kernel. And then check after the installation that in your menu.lst you have the entries for the new and current kernel.
Also, it would be wise to make a back-up of the data on your hard drive (e.g. your /home) before changing the kernel. :-)
@Patricio
The file is /boot/grub/menu.lst
I think during the installation of a new kernel, the post install scripts executed by dpkg are updating grub and its configuration files. So you should have nothing to do. But I would still recommend you to back-up at least the /boot/grub/menu.lst before installing the new kernel. And then check after the installation that in your menu.lst you have the entries for the new and current kernel.
Also, it would be wise to make a back-up of the data on your hard drive (e.g. your /home) before changing the kernel. :-)