How do I select a root file system when partitioning?

I want to install Ubuntu on the C: partition where my Windows 7 is, simply to replace the systems. I've also tried to install it on another partition (without formating it), which failed!

All I get is:

No root file system is defined. Please correct this from the partitioning menu.

I want to install Ubuntu without formatting any of my partitions. Is that possible?

Solution 1:

It sounds like Wubi might be better for you... if you don't want to rearrange or format any of your partitions, you can consider using Wubi (see this page for more information about Wubi).

Normally I do not recommend Wubi, but if you absolutely do not want to change your partition structure or format any of your partitions, that might be the way to go.

Solution 2:

You need to select a root file system in the advanced partition editor, select your hard drive where you want Ubuntu and set the mount point to /.