Latest official update 2.1 (UXP update)
It's for X10a but works just fine with X10i
go here and download the X10a-2_1_A-_0_435_EW.ftf file
http://forum.xda-developers.com/showthread.php?t=935407
download FlashTool 0.2.4
http://forum.xda-developers.com/showthread.php?t=825675
Install it
inside there will be 5 folders
Custom
Drivers
Firmwares
Loaders
X10Flasher_lib
put X10a-2_1_A-_0_435_EW.ftf file inside "Firmwares" folder
click on X10FlashTool (Application)
click on Connect (it's a button)
Select X10
Press Ok
it will ask you to connect your phone on Flashmode (turn off your phone, press the back button, then connect the USB) press OK
Click Flash
rooting and/or flashing firmware other than the one offered through PCCompanion or Update Service could violate your warranty (unless is restore to its original firmware)