Changing system sounds with mp3
I dont know if anyone has done this yet or not but I was able to change out all the sounds on my g2 with using a root browser and ringdroid.
I used ringdroid and cut the mp3 to the length I wanted and saved as a music file, then go into the file manager and rename the file the same as the file I want to replace in the system\media\audio\ui folder.
Note: when renaming the file instead of .mp3 add .ogg to the end of the file name
Also be sure to back up any sounds you change out first