/dev/hda is not a partition
/dev/hda5 is a partition
mount /dev/hda5
Or more properly, as root:
mount -t reiserfs /dev/hda5 /mnt/hda5
Replace filesystem type and mount point with
whatever is applicable to your system (/etc/fstab)
Once mounted, you can chroot into it.
Didn't you try clicking on the icon first?
Much simpler.