Yes, you must choose for a partition the mount point "root" ===> /
Just select "the old Linux partition and clicked format" is not enough...
If you want you can also choose for another partition another mount point, e.g /home
About the file system type, I would advise you to choose between ext3 (it was supposed to be the "native" Linux filesystem) or JFS
K.I.S.S. ===> "Keep It Simple, Stupid"
"Simplicity is the ultimate sophistication." (Leonardo da Vinci)
"Everything should be made as simple as possible, but no simpler." (Albert Einstein)