In need for some more power as the 6300 isn`t quite cutting it for my uses (Flight Simulator X, Photoshop editing). I have adjusted the FSB on the mobo from 266 to 285 which is allowing me to run at roughly 2 GHZ. This is all i have touched.
I have been reading the tutorial at the top of this forum and after a little tinkering in the BIOS i`m a little nervous especially as my computer is new and it switched itself off automatically after i exited the BIOS!  8O  
 
Is it imperative that i follow every point in this tutorial?  I don`t really want to overclock her like crazy, i would be happy just to squeeze a bit more to maybe get to 2.25GHZ. My system temperature ranges from 43-48 at the moment depending on what i`m doing, is this normal?  I have been seeing other people with the same processor running well over 3GHZ at the same temperature - i understand there cooling must be far more advanced than mine but this just seems insane.  
 
My RAM is rated 667mhz but its overclocking at 712mhz (i believe this is because i overclocked the FSB of the CPU so the RAM follows suit). Is it advisable to overclock your RAM?
 
For your info my system is as follows:
 
Gigabyte GA-965P-S3
Intel DC2 6300 running at around 2GHZ
Stock Intel fan which came with my MOBO bundle
2x512MB sticks of RAM (Dont think they are a known brand, came with my mobo bundle) and 1GB stick of Kingston ValueRAM - all 3 sticks 667mhz.
Sapphire ATI X1600 Graphics card
2 SATA hard drives
1 IDE hard drive
 
My Mobo bundle is here: BROWN DOGS MOBO
 
Thanks for any input and apologies if this info is elsewhere on the board but i cannot find it!    
Any other observations about my system would be much appreciated, i have never been too sure about my RAM configuration ie.having 2 512mb sticks and a sole 1GB stick.

I can't comment on all your questions but I do have the same motherboard as you, and whenever you make changes (voltage, fsb, etc) for overclocking it will power off after you save and exit, so know that (for the most part) is normal.  If it does not boot after it powers itself off then you might have to clear the CMOS and start over with adjusting your settings.
 
I followed this guide for the most part and it worked with my proc and mobo.
Click here
 
If you haven't already I would also suggest getting a nice heatsink/fan for your processor if you are going to overclock.
 
Hopefully this helps.
 
my system -  
 
Intel C2D E6400 @ 2.92 Ghz
Gigabyte 965P-S3 (Latest Bios - F5)
2x512MB Corsair XMS DDR2 800
Sapphire ATI X850XT
WD 160GB SATAII and WD 80GB SATAII
Artic Pro 7 CPU Cooler
Antec PSU 500W
XP Pro SP2

Do exactly as the guide says, but instead of setting the FSB at 333Mhz go just for 322Mhz wich would be 2.25Ghz. After that, check temps and stability and start lowering the voltages.

 
I also have a Gigabyte board but the DS3 instead of the regular 3. As long as you have the latest bios, you should be able to overclock to 3ghz and beyond (I'm at 3ghz with stock cooling) with little sweat. The only thing that would stop you is either your ram and cooling. Check your ram timings and your ram frequency.
 
For my 3ghz, here was what I did to the bios:
Disable all that EIST and EMT stuff
Disable all those fan controls to make it cool as much as possible
+0.2 volts to Dimm
+0.1 volts to FSB
+0.1 volts to MCH
1.4000v for vCore
Change ram multiplier to 2
 
Hope this helps

Just follow wuss' guide, you wont have any problem im sure. even at 333mhz x 7 you would still have rock stable system.