It has to be flashed by ODIN @PJ147 Use the included files for ODIN and the instructions from either link
@King Kaze - I was using UK XEU but it was only 2.3.3, This is 2.3.6 and includes Three's network tweaks which makes my 2G roaming a bit better, but completely useless still. I have to wait 2 minutes for 0.facebook.com to load on Opera! If I use Opera on any other phone on 2G m.facebook.com loads quickly. I'm thinking it's Three restricting how fast things can download/tx-rx on 2G, Their websites load alright in seconds... I asked them about this and they denied that they restrict speeds on 2G which makes me laugh.
Nexus 7, Galaxy Ace II.