UK, O2, GT i9000, rooting advice please

I am VERY unhappy with my Galaxy S. I loved it when I first got it, 18 months on, several updates later, I want to break it. Ever since I upgraded to 2.3.3 there have been so many issues/problems/things I just DON'T like at all! I now officially do not like this phone.
My friend has told me to root my phone and change the firmware to a more acceptable one? They said it's the good thing about Android, if you don't like it, change it. Possibly I could downgrade back to one I liked before? Or maybe I could upgrade to something new?

If it helps, my phone is O2 branded (i bought it in the O2 shop and it has a millennium dome background)
I live in the UK.
Model: GT-i9000
Firmware: 2.3.3
Baseband: i9000BWJV2
Kernel: 2.6.35.7-I9000XWJHV-CL18483 root@DELL101 #2
Build: GINGERBREAD.XWJVH
(I know all this will mean something to someone out there...)

Basically, can someone please explain simply HOW to root my phone, what do I need? (i've heard of Odin? Does that make sense?) is it worth it? What acceptable firmwares are available in my country? I am not a technical retard, but I am really not clued up on this sort of thing so any help would be appreciated please.

Yeah... Everything you just said makes not much sense to me! haha! If you could explain it in a more simpler term I could understand? It's all new to me so trying to work out what all the terminology is...

If I were you Google it and do research on how to flash & using Odin..before using Odin..
Have you checked your apn settings..?

Flashing is when you update the phone either firmware, kernels, mods etc..
Have you tried the easiest method, samsung kies software..connect your phone with computer using the usb cable, open kies & let it update automatically to your phones latest firmware (I believe is gingerbread xxjvu)

Read this
http://www.theandroidsoul.com/xxjvu/ (to flash firmware)

How to root
http://www.theandroidsoul.com/root-xxjvu-firmware/ (root phone)

Hope that helps