Offtopic disk partition question

[Sean Murphy <murphy erim-int com>]

This is definitely an off-topic post, but I'm not sure where to look for
the answer, so if someone is willing to answer the question off-list or
point me in the right direction, I'd appreciate it.

We've got a Linux box running here at work that was partitioned kinda
awkwardly and we'd like to correct it. Current setup is:
[murphy]$df -h
Filesystem            Size    Used   Avail   Use% Mounted on
/dev/hda1             1.9G  1.2G  607M    68%      /
/dev/hda5             1.8G   54k  1.7G         0%      /tmp

Obviously there is no reason /tmp need to be that big, so I'd like to
change it's mount point (maybe to /usr or /home? - any suggestions here
would help also), but I'm unsure how to do it CORRECTLY.  I know I need
change the entry in /etc/fstab to be what I want, but what is the right
way to get the data in the correct place before I make the change?

Let's assume I want to make hda5 mount as /usr, I'm envisioning I need
to do something like:
As root, cp -R /usr/* /tmp
change the entry in /etc/fstab to mount hda5 as /usr
reboot

Is it that easy?  I'm not too worried about losing the data that is
currently in /tmp - after all, it is just temp data!
Thanks in advance