Download the ZIP file and read the readme file ... read the complete file b4 fidling with the w800.exe
save ur CDA and IMEI number b4 converting your phone so that if you want to use k750i firmware again then you can change back to old cda and use SEUS (update service).
** Make sure your battery is fully charged **:)
Note : This conversion is possible since both K750i and W800i have the same hardware dont try this on any other phone.;)
File download