Take Note that there are different firmwares available for each region. The Firmware mentioned by faixan.6x in the above guide is the Asian one.
There are others availble. Here are the latests version no's for each region.
I570EXXJD4 European version
I570EDXJC4 Asian version
I5700JPJC1 African version
I have the latest European version. PM me for a Rapidshare link.
Phone: Galaxy i9100 SII: Now using Galaxy TAB7.7. Sowheat!!