What is the p1, p2, p3... on my Power Mac G5?

So years back I bought this old power mac g5 2 GHz from my high school because they were selling all their old macs and getting new ones. All i used it for was photos and I utilized the Adobe software already on there. When I got it, it had p1-p7 shortcuts on the destop and on the side bar in the finder. What are those?? are they just like memory slots in the computer? or are they just shortcuts and icons that my school used for us to save things on?? I'm confused because under my user in finder I only have right now 1.51 GB of memory?? but in these shortcuts I have about 27 GB in each (they're all different). why is this? Is there any way for me to get rid of these P drives and just use "My Documents, My Pictures" to store all my stuff?? I'm in the process of clearing all the drives out and i just dont get how i have 1 gb under my user :/ is that acting as like my RAM? ugh..

right now the start up disk is labled as Macintosh HD with 1.31 GB of memory. the last times i had used it I could never edit photos because it was saying my start up disk was full..