how do you uninstall the previous version of swype?
Go to your phone settings then Applications> Manage Applications > Then find Swype and Delete
The leaked installer is on your SD card so you should delete that as well.
I didn't delete it. Mainly because I had already tried to install over the previous version and I wasn't sure if I was seeing the installer from the previous version of the installer I had just downloaded. In any event, once I uninstalled the old version of Swype the new one installed perfectly. Worth noting, I suppose that there were (at least) two "leaked" versions. I was running the one that came out a couple of months ago. Things may be different for the hacked (smaller) version that was discussed a few days ago.