Customising the ringer for SMS seems to be quite a chore, following are a few methods that i have discovered for customising SMS and call ringtones.

method #1: Copy the mp3 or your choice of music file to My Device\My Documents. Any mp3 there could be set as ringtone for SMS, call, etc. Basically any event could be customised with the music file placed here.

method #2: Copy the file to My Storage. You will have to keep the file on the root folder of the16GB storage space. Similar to method 1, any files placed here could be set to any events.

method #3: Place the file in My Device\My Documents\My Ringtones. Files are can be set as caller ringtone only.

method #4: From any folder, just right click on the audio file (tap and hold), select Set As Ringtone. The system will copy the file to the folder mentioned in method 3 and set it as the caller ringtone.