I'd go for the i3 as well - had that model until I just upgraded to a faster CPU (do a fair share of video editing). In any case, the i3 is quite good and nimble - do increase the RAM though since both Lion and Mountain Lion are memory hogs. You can get RAM here:
I'd go for the 2 x 4 GB matching kit and you'd wind up with 12 GB which is what I have - more than enough for what you want to do and then some.
steve359: Most Core2Duo are so outdated they cannot run MountainLion
That's not quite right. The crucial CPU requirement for running Lion and Mountain Lion is a 64-bit processor, so any Mac with a Core 2 Duo (or later) processor should be fine. This includes all aluminium iMacs.
However, Core Duo processors are 32-bit and hence will not run Lion, Mountain Lion or any newer version of OS X. (Perhaps it's worth noting that Apple have never sold a Core Duo iMac.)
jayj320, while you've probably already made your decision, I'll offer my opinion on the off-chance that someone else is in a similar predicament.
With a 2009-11 iMac, like the one you've described, the 5% difference in CPU speed is unimportant on its own. However, i3 CPUs use a much faster system bus than Core 2 Duos, and i3 RAM is about a third faster. Finally, in mid 2010 the i3 iMacs got a faster graphics card.
In benchmark terms, the Geekbench2 scores are as follows. (The reason for the third benchmark is in the last paragraph.)
- 4178 - for early 2009 iMac with a 3.06 GHz Core 2 Duo
- 5837 - for mid 2010 iMac with 3.2 GHz i3 CPU
- [3865 - for early 2008 24" iMac with 2.8 GHz Core 2 Duo]
What does all this imply? For "web and email" work, either iMac will be more than fast enough and should support future versions of OS X for some time.
In fact, I've written this note on an "early 2008" 24" iMac (the last of the three iMacs listed above) running Mountain Lion, and I cannot say that I've noticed any speed problems with this supposedly antedevulian system since I bought it five years ago; And this system has a benchmark of just 3865!