In the zone
Since K750i and W800i have the same hardware, u can easily convert it to W800i. The main difference is that when you start the phone, you get an option to start the phone in normal or music mode. And most importantly you get the much advanced WALKMAN media player and even your sound quality improves. But beware only older models of K750i (CID36) can be flashed and not the newer (CID49). It also voids your warranty with Sony Ericsson.