iPod I'm going to replace the battery in my 3G.

I did this with my 3g in several months ago. Does the battery you are getting come with tools to open the ipod?
Mine did. It also had a CD with a video tutorial of how to do it. It was pretty easy and straightforward. You just have to be careful with a few wires so you don't pinch them when you snap the case back on.

i found the plastic tools with mine (from eurobatteries.com) were rubbish, the best i found was to use a sharp knife (a thin plastic blade might also work) and insert it between the plastic and metal and pull the metal back then put something like a key in the gap and work around the edge, then you tease the back off, lift out the HD out and the battery is in a corner. The knife did scratch the case quite badly though. The main thing is to be careful, and make sure the hold switch is lined up with the switch underneath.

people say its really hard to do. I found it was actually really easy.

The copper sheet which connects the HD to the mainboard is held in by a clip which can be pulled out quite easily.

I managed to take my 3G apart, and when i put it back together, it was still making clicking noises which it made before my disection. I completely gutted it an re-built it.

When you replace the battery, try to put the wires back where the original ones were. You may need to loosen the screw in the corner to do this.

I replace the battery on my 3G(which was lasting like 45 minutes), and I had to end up getting a knife to get between the plastic and the metal. If I used the tool they gave me it mashed the plastic in so bad, that it was starting to piss me off. So then I got a small pocket knife and made the metal separate from the plastic just enough to stick the "special tool in" (Screwdrive for a pair of glasses).

Then you just work your way around and push and pry, then it's open, kinda scary but it was fairly easy. Just make sure you start in the right place. The directions came with the battery, but I googled for it and found much better directions. Hope this helps.

Might be a good idea to do some guides about how to replace the battery and hard drives in the different iPods...

I replaced mine using the plastic tools provided from iPodResQ. Took me about 3 minutes.

The tools vary in usability. Maplin usually sells... um... how to put this without getting sued...oh yes, products which approach the high quality that the Ratners chain of jeweller's shops was known for, so there's no way of knowing whether the supplied tools are any good.

If the tools supplied should fail and you want a surefire way to open a 3/4G without damage without improvised knives etc, go to a local music shop and get yourself a guitar pick. I'd suggest a Dunlop Tortex 0.73mm (it's yellow and fairly hard).