First, well done on your first oc - feels good don't it? ;-) Quite a bit here, but bear with me:
Now about your board, it doesn't look to great on the gigabyte website but thankfully it is possible to change the cpu multiplier and voltage on the chip itself if the mobo doesn't allow you to make those changes (I don't think it does). I assume you are currently running at 110fsb - your next job will be to unlock the multiplier on the chip, and this can be done with an ordinary pencil. Just join the 4 L1 bridges, and then set the other bridges as desired for the correct mutliplier and voltage (I'm sure this makes no sense so here's a link: http://www4.tomshardware.com/cpu/00q3/000711/index.html
The best way to do this, cos it is a bit of a hassle, is to cut all the relevent sets of bridges, and then join the ones you want with a pencil - as this can be removed quickly and easily, making it a bit less fuss to change the multiplier than if you used defroster repair paint or something. Once you've found the max multiplier and voltage the cpu can take, join the bridges with something more permanent like a conductive pen (pencil can wear off after a while). Seeing as you know you can do 880, try 900 first, and raise the volts by 0.05 or 0.1 - that way you can play around with the fsb a bit, and if you can make it to 950 or higher change the multiplier to 9.5, then raise the fsb again. Take the voltage to 1.85 if you need to for stability, but (and it's a big but) look after your temps.
60C is the absolute max I'd consider, but 50C is more sensible, and 40C-45C is ideal, so try for that sort of range. If your temps at the moment are close to 50C you really need more cooling before raising the voltage.
If you have any problems with closing the bridges or cooling or anything, just post. Welcome to the wonderful world of ocing!