When you install you have options where to install grub, but first.....
I remember my first attempts at partitioning and installing multiple OSs. If I had it to do over I would read, read, read.
Start here >>
http://www.pclinuxos.com/forum/index.php/topic,76061.0.htmlOld-Polack has posted several great tutorials and tips about all this. Use the forum search and gather all the info you can so you fully understand what's going to happen. There is plenty of help here if you get stumped along the way.