For old 2008 iMac users
I just recently found out that these iMacs, which were officially shown to only support 4 gigs of ram, can in fact support 6 gigs. I own one myself and I was prepping it for sale and decided to upgrade the hard drive with an OCZ Vertex 4 SSD I got for a really cheap price and with the 6 gigs of ram just to see what the difference would be. I also "downgraded" back to Snow Leopard.
Well, in a nutshell, I have decided to keep the old iMac because the performance difference has been quite dramatic. I use Lightroom and Photoshop Elements for my photo needs at this time and boy what a difference in speed and multitasking. Most standard apps open on one bounce and boot time is now 20 seconds, even with two external drives connected.
Anyway, I just thought I'd share my experience with this forum in case someone owns this older iMac.