How do I find out which boot loader I have?

If you have the /etc/lilo.conf file then you are using LILO (LInux LOader) This means that if you type lilo for example you should see the command dialog for the lilo booter.

If you have the /boot/grub/ directory then you are using GRUB (Grand Unified Boot Loader) This means that you should be able to use all the grub file like grub-install,grub-reboot...

Ubuntu 9.10 was the first version to use GRUB2 https://help.ubuntu.com/community/DualBoot/Grub

UPDATE:

Here is a script to check inside the first sector of the hard drive for what boot manager it is using:

Assuming your hard drive is at SDA then:

sudo dd if=/dev/sda bs=512 count=1 2>/dev/null | strings | grep -Eoi 'grub|lilo|acronis|reboot'

will tell you which bootloader you are using.

You can imagine the rest...
The list of boot loaders is here: http://en.wikipedia.org/wiki/Comparison_of_boot_loaders and http://wiki.debian.org/BootLoader (For Debian based distros)
Also if you want to SEE the real binary output then add -a to the grep part. For example:

sudo dd if=/dev/sda bs=512 count=1 2>&1 | grep -a GRUB which will show you the data in that first block.

Now with this new information you HAVE to find the boot manager you are using.

The boot info script will detect all kinds of useful information about your boot configuration:

http://sourceforge.net/projects/bootinfoscript/

Use the dd command to read the boot sector, then use grep to know your bootloader:

dd if=/dev/hda bs=512 count=1 2>&1 | grep GRUB
dd if=/dev/hda bs=512 count=1 2>&1 | grep LILO