Trying to find if can upgrade RAM on early 2009 iMac 2.66. Has 4GB. Says has 2 slots each accepts 1067 MHz DDR3 module

Question

I have an early 2009 24-inch iMac (2.66 intel core 2 duo) with 4GB memory and am trying to establish if I can upgrade the memory, hopefully to improve performance and prevent regular/occasional slowdown/sticking. Spec tells me I have 2 memory slots, each of which accepts a 1067MHz DDR3 memory module. It says all are currently in use and shows 2GB in each. So, question is can I upgrade or is this the max it can take? I'd like to upgrade, say, to 8GB, 4GB in each slot, if they have the capacity for that, which isn't clear.
Also wondering if this will improve performance - i.e. prevent occasional but sometimes regular sticking/slowing of performance, spinning wheel, etc. Activity monitor often shows just single or three-figure MB 'free' - mostly as a result of having multiple web pages open (have 8 saved tabs regularly open). That said, all my problems started some time ago when I 'upgraded' to Lion. But general view seems to be that memory is best bet for such problems.
If I can upgrade, am I right to understand that Mac memory is way overpriced and that it's OK/safe to use third-party memory and that a total non-expert can install that?
Any help appreciated.
geoff

Answer 1

Each slot can accommodate up to a 4GB module; upgrading both slots will max out your RAM at 8GB.
How much performance boost you see depends on many variables, one of which being your version of the Mac OS, which we don't know at this time. My experience is that, for the average user (word processing, web browsing, e-mail), 4GB RAM is fine up to Mac OSX 10.8 Mountain Lion. Please tell us what OS you have and how you use the computer (task-wise) and we can better suggest if an upgrade will help.
Install RAM in an iMac is an easy, 10-minute and at-home job. Video instructions here:
http://eshop.macsales.com/installvideos/imac_mid_2007_mem/
RAM is expensive if you get it from Apple. Fortunately for you, they only sell extra RAM for the latest models. For over a decade I have bought RAM from one vendor online and never had an issue. I find their Mac RAM roughly equal in price to RAM for the "Dark Side" computers. I am supporting about 25 Macs between family and friends, so have some credibility as an advanced user.
If you give us a rough idea of where you are located, we can suggest reliable vendors of Mac- compatible RAM.