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Be careful - the link you posted is for DDR2 RAM. That would be correct for any aluminium iMac before the current one, which uses faster DDR3 RAM. As a rough guide, if your iMac has a base that tapers towards the front then you can use DDR3.
 
That's the right memory then. When it arrives you'll probably find it's even branded the same as the stuff in your iMac already - Crucial are brilliant!
 
Shall I go for it then?

It will all work perfectly and speed my iMac up when im gaming, video animation and stuff?
 
If your iMac came with 2 gb ram when you bought it then it's probably 2x1gb and buying this wont do you any good (unless you buy 2 of them).
 
Given how much it costs (i.e. not that much) I think it is generally thought to be a really good value upgrade. It's hard to tell whether you, in particular, will see a significant improvement but video stuff is exactly the kind of thing that demands plenty of memory.

You can always ebay your 2 1GB SODIMMs too.
 
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