First -- always have backup copies of anything important before installing anything to hard drive. Also, have recovery disks made for Windows just in case you make a mistake and wipe it out.
Each Linux distro may have a slightly different installation procedure. So be sure to read the installation instructions on the sites for those you are installing. Below is a general description of the process for installing multiple distros.
When you install a linux distro, it will usually install the grub bootloader to the MBR (Master Boot Record) of the hard drive. The MBR is the first 512 bytes of the drive and it holds the partition table of the drive and the first stage of the boot loader. That first stage of the boot loader points back to the rest of the files needed to finish booting the operating system. So part of grub is in the MBR and the rest is either on the "/" (root) partition or a separate /boot partition (if you made one).
Right now you have Windows XP and Mint 16 on the computer. Mint 16's grub boot loader gives you the choice of both to boot up with. If you do a standard installation of Peppermint, then Peppermint will install its grub bootloader to the MBR and take over the duty of booting and showing choices of OS's (Operating Systems).
But what if you later decided that you didn't like Peppermint and you deleted its partition?
You wouldn't be able to boot into anything anymore because its bootloader was in control, but now the second stage boot files are gone.
That
is fixable. But it's much easier to just avoid the headache in the first place. So, the better idea is to keep control of booting with a distro that you know you will likely keep (Mint in this example). You do that by making sure any new install (Peppermint) does not put their grub on the MBR. (If you have one hard drive, the MBR will be
/dev/sda -- just sd
a, with no partition number after the "a".) Point Peppermint's grub installer to its own root partition instead. (The root partition will have a designation like
/dev/sdaX, where "X" is a number corresponding to the root partition for that distro. Eg. If Peppermint's root partition is the third one on the disk, it would be
/dev/sda3.) After the installation, you will not see Peppermint as a choice in the boot menu yet, because Mint is in control of booting and doesn't know it's there yet. To find the new OS, run sudo update-grub in a Mint terminal window. On the next reboot, the choices will be updated to include all three OS's.
(NOTE: You only need one swap partition -- not one for each distro. They will all share useage of that same swap partition when you boot one of them up.)
One other thing to keep in mind is that on most computers more that 1-1/2 to 2 years old (and some new computers as well), there is a limit of 4 "primary" partitions. To get around that limit, one can have 3 "primary" and 1 "extended" partition. The "extended" partition serves as a container for "logical" partitions, of which there can be many. So you need to keep that in mind and plan for using "extended" and "logical" partitions when installing multiple operating systems.
Here is a good tutorial on how to use the GParted partitioning program, which is included on many live distros:
GParted partitioning software - Full tutorial
Here's another guide to partitioning:
http://www.sysresccd.org/Sysresccd-G...N-Partitioning
, im sorry i don't understand some terms.. i'm already creating an empty partition with GParted.. what does "install without bootloader" and "sudo update grub" mean? im really sorry i don't know 
