By performing an upgrade, you can migrate (or convert) your existing ext2 filesystem to an ext3 filesystem. This operation will preserve your existing files.
The advantage of migrating to ext3 is that you will have journaling filesystem capabilities. The ext3 filesystem do not have to be fscked after an unexpected reboot, unlike the ext2 filesystem. This can drastically reduce the amount of time for the system to come back up and be ready to use.
It is therefore recommended that you choose to convert your filesystems.
To do so, select the partitions to migrate to ext3.
When you are done, click Next to move forward.