If you use the firmwares which I linked to in the tutorial, it will put you on the current latest 2.2 firmware for the UK (JPO). I presume you are in the UK? After doing this, Kies will say you are already using the latest firmware if you try and upgrade. This will not stop you getting future upgrades, if anything it will make them available to you earlier, because this firmware isn't network branded, meaning that you will get the firmware when Samsung release it, and you won't have to wait for your network provider to apply their junk to it.
You need to root your phone, try searching the app market for
RYANZA'S ONE CLICK LAG FIX. That app has a built-in rooting/unrooting function. After that you need a file explorer that works at root level to back up your /efs folder. I highly recommend
ROOT EXPLORER. It's a paid app but totally worth every penny. (Well, every cent.)
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