You can use your own music from your PC as ringtones, install this software from http://www.ifunpix.com on your PC and start downloading music to your mobile phone and PDA directly from your PC using it's WAP interface. You don't need bluetooth device, sync cable or to be at home at all. Your entire music collection is available to you from anywhere, that way you don't even need a big memory card on your phone because you can download anytime.
Get the latest nokia pc suite from their website or the phones disk and convert through that OR if they are in mp3 then just bluetooth them onto your phone, save them to phone memory and select, set as ringtone from the options on the phone...
well theres another way to put ringtones on ur phone by going to phonezoo.com. u make an account, then make a ringtone and put the length for 30 second and they'll send it to ur phone. but u gotta have internet on ur phone...u can also do it thro bluetooth