Is it a good idea for me to add RAM (3 in 2 slots) before upgrading to latest updating system? I have a mid-2007 IMac desktop.

If you're running Yosemite "OK" right not, you should be alright with El-Cap. Apple says that machine will support 4 GB of RAM, you can (or used to be able to get) kits from OWC that would allow it to go to 6, but I honestly don't think I'd sink the money into a machine that old. 8 years is a very respectable lifetime for any computer.

Rslep wrote:

I have a mid-2007 24" IMac desktop. My current operating version is OSX Yosemite. My Memory installed is 3GB (1GB in 1 slot and 2GB in second slot.)

DO you think it would be advisable to add more memory before upgrading to OX 10 El Capitan? If so, how much and how do I proceed?

Also, what will happen to my photos in IPhoto and Aperture?

Thank you,

RSlep

I would recommend upgrading to the maximum amount of RAM a 2007 iMac can accommodate which is 6GB. You can install 1 x 4GB and 1 x 2GB DIMMs in each slot. OWC (www.macsales.com) makes a kit for just that, if you are interested in it, the link is:

http://eshop.macsales.com/item/Other%20World%20Computing/5300DDR2S6GP/