Seems a lot of people don't know how to do this........
Open contacts
Goto the contact you want to change
On the screen you select either to dial or message press the menu softkey
Select options
Select ringtone you want for that contact
Works for me
Open contacts
Goto the contact you want to change
On the screen you select either to dial or message press the menu softkey
Select options
Select ringtone you want for that contact
Works for me