Watch this video (not my video!) if you want to try this user interface on your Xperia Mini Pro the steps are below. I have been using this since I bought my Mini Pro and love it, it is much better than the default Home launcher UI and there are a lot of reports on forums and blogs that it improves battery life. I get over 48 hours off a full charge so perhaps HelixLauncher is to thank for that.
This will not delete the current Sony Ericsson Home UI, it basically works "instead" of it if you install it (and when prompted if you set it as your default) -- you can safely uninstall it if you do not like it.