Q: upgrade my old iMac?

Upgrade the hard drive to a newer one, upgrade the ram at least to 2GB, and install Snow Leopard on it. Go to "About this Mac" and see if it has a Intel Core or Intel Core 2. If it has a Intel Core, upgrade to 2GB of RAM and Snow Leopard. If it has an Intel Core 2, upgrade to 4GB of RAM and upgrade to Lion. (Lion requires Core 2 processor). Note that upgrading the hard drive is an advanced process and if you are not sure about upgrading the hard drive, don't do it.

Both Core and Core 2 iMacs use DDR2 667MHz PC-5300 memory and SATA hard drives. NOTE: iMac Mid-2006 (iMac 4,2) will not support 4GB of RAM. To see your ID go to: About this mac > More Info and you will see: "Model Identifier". You can add in any 3.5" SATA hard drive up to 3TB. For the RAM, you can find some there: http://eshop.macsales.com/shop/apple/memory/iMac or you can buy one on eBay for cheap, but it may not work if you don't choose the right memory.

One last note: BACKUP! Backup all your data before performing any upgrade!

EDIT: Your Mac is quite old already. You should save for a new one, yours will stop being supported in a few years, it's low in specs and it won't stay to the latest version of OS X. Macs do not have endless lifespan. If you really don't have the money to get a new one, you can upgrade it but one day you'll have to. Many applications aren't supporting SL anymore and in a few years Lion will be unsupported too. So you might think about upgrading.

With the age of his iMac and the fact the while OP's iMac can take (2) 2 GB RAM modules for a total of 4 GBs of RAM, that model iMac will only recognize about 3.2-3.4 GBs of the total 4 GBs of RAM installed.

OP should upgrade their iMac's OS X version to OS X 10.6.8 Snow Leopard and stay on that OS X version AND NOT UPGRADE ANY FARTHER.

OS X 10.6 Snow Leopard is still being supported and updated at this time.

It maybe awhile before OS X 10.6 support ends...who knows?

No need to upgrade to the latest OS that will just make the OP's iMac much slower to function and use.

OS X 10.7 and 10,8 are computer resource hogs.

Those OSes use more CPU, GPU, RAM and hard drive resources than any other previous versions of OS X.

This fact is evident in the fact the brand new iMacs are now shipping with 8 GBs of RAM to  make OS X 10.8 Mountain Lion functionally usable.

The OP's 2006 iMac is simply not up to the challenge.

Correct and reliable Mac RAM can be purchased from online Mac RAM sources Crucial memory or OWC (macsales.com).

If you are not from the U.S., both OWC and Crucial Memory have international shipping. Crucial has various websites that cover the different regions/continents of the world.

You paid way too much money for Apple's RAM!

Third party RAM is waaaaay cheaper.

Here's the cost of RAM for your iMac model from OWC (macsales.com).

http://eshop.macsales.com/item/Other%20World%20Computing/5300DDR2S4GP/

Nice. After that, you could sell it for a good price when you'll get a new iMac (520$ according to Mac2Sell).

P.S. Did you backup your data before upgrading?

MichelPM wrote:

 

You paid way too much money for Apple's RAM!

Third party RAM is waaaaay cheaper.

Here's the cost of RAM for your iMac model from OWC (macsales.com).

 

http://eshop.macsales.com/item/Other%20World%20Computing/5300DDR2S4GP/

Yeah but he needs to upgrade the RAM and the hard drive by himself.

RAM is the only thing that IS user installable.

bargemule wrote:

 

as for the ram, I have no skills at all regarding such installations. that's why I took it to the pros. no idea where they are buying it from.

This is how easy it is to install RAM.

This is designed for non-conputer techs/upgraders to be able to easily do.

http://support.apple.com/kb/HT1423#3

http://m.youtube.com/?reload=7&rdm=u49pb1p7#/watch?v=YD2yMTzh3gk&desktop_uri=%2F watch%3Fv%3DYD2yMTzh3gk

FYI

This is, partly, what your $360 is paying for.

You are wasting your money. 360$ is a quarter of the price of a new iMac. I understand if you don't want to upgrade the hard drive because you think you risk breaking the Mac. But the RAM, it's so simple to upgrade:

-Unscrew 2 screws (BTW philips screws not weird torx screws)

-Pull the handle

-Remove the memory

-Add new memory

-Push the handle

-Screw 2 screws

-Realize how much money you saved

I've managed to upgrade my iMac G4's PSU even I'm not an expert. Upgrading the power supply in a G4 is a pain in the butt, but that was the first upgrade I ever did on any Mac! And I succeded! So you can upgrade the hard drive this way:

http://www.youtube.com/watch?v=MijEjwDk5Is

and the RAM this way:

http://www.youtube.com/watch?v=YD2yMTzh3gk (link by MichelPM)

BTW for the ex hard drive, you can format it in Mac OS Extended, Extended (Journaled) or FAT32 to make it work on your Mac. If you use PCs then format it in FAT32.

Did you even watch the video?

It will take you, at the most if you are really careful about these things, 15-20 minutes to actually add the RAM.

Most inexperienced users can usually do this in 10-15 minutes, tops.

Third party RAM is soooo much cheaper than Apple, so your logic eludes me.

Just because they are replacing the hard drive doesn't mean you need to have them replace or upgrade the RAM, too!

Especially at Apple's costs for RAM PLUS Apple's hourly rate to install that RAM.

Ridiculous!

You are saving more than a just couple of dollars by doing this yourself.

To each is own. You have the finances do what you will.

Good Luck!

Hope you have a complete backup of your data as Apple is NOT responsible for lossed data due to hard drive failure/replacement.