Looks like there is no separate home partition, so you need to first backup
anything you wish to save off the hard disk and then go ahead with the
install. I too suggest when installing, do make a separate home.
You can have as many OSes as you wish on one computer but you cannot have
more than 4 primary partitions (if using the popular MBR scheme). If you've
already have 4 primarys, you need to remove one and make an extended
partition. Then on the extended partition you can make as many logical
partitions as you wish. I've never seen on OS you cannot remove.
Here's more info on that
http://en.wikipedia.org/wiki/Disk_partitioning#PC_partition_types
