First, you will need to download an extension or two.
You will need to download Adblock Plus. The original Adblock, I'm quite sure, is no longer developed.
After you download Adblock+, you will need to do two things.
1) Install filter lists. (A screen will pop up once you restart Firefox)
I suggest using EasyList, but if you go here, you can install EasyList+EasyElement in one.
Note: Filterset.G Updater is no longer necessary
Now for the important part, the part you are all here for.
Here's how to block IGN specific ads and make IGN run so much faster:
2) Install custom filters to Adblock+
You will need to go to Tools --> Adblock+ (or you can press Ctrl+Shift+A)
Once there, you can do one of two things: Install this custom filter, or put in the list manually.
Here's the list you need to input:
http://wrapper.ign.com/*
http://de.ign.com/*
http://scripts.snowball.com/*
http://ads.ign.com/*
http://atax.ign.com/*
http://wrapper.gamespy.com/*
http://eyeblaster.ign.com/*
http://fimserve.ign.com/*
Also:
To install the custom filter, go to "import filters" and import the custom filter from above.