Q: best operating system?

It cannot run Snow Leopard but can probably run Leopard. You will be able to use a more current version of Safari that way.

The highest you could put on ot is 10.5 (Leopard) in the last (2005) models of eMac.   Those older PowerPC G4 machines will never run any faster than they do - its an eight year old obsolete architecture now.   I think you can go up to 2GB RAM though in the 2005 models, which might help a fair bit, especially if still running with the original RAM (which was something like 256MM-512MB, if my memory is right - my Mom had one of those for awhile).

Look at the memory upgrade options at http://eshop.macsales.com

Hello,

Leopard requirements/10.5.x...

    *  Mac computer with an Intel, PowerPC G5, or PowerPC G4 (867MHz or faster) processor

minimum system requirements

    * 512MB of memory (I say 1.5GB for PPC at least, 2-3GB minimum for IntelMacs)

    * DVD drive for installation

    * 9GB of available disk space (I say 30GB at least)

Classic/OS9 Apps no longer supported.

May be available from Apple again...

https://discussions.apple.com/thread/4720126?tstart=0

Trouble is Apple no longer sells it, ??? check eBay & such for the Retail version, not the Gray Discs...

http://www.ebay.com/sch/i.html?_nkw=mac+os+x+leopard+retail+10.5

There are workarounds if the 867MHz CPU is the only hangup...

http://sourceforge.net/projects/leopardassist/

http://lowendmac.com/osx/leopard/unsupported.html

If System Profiler (Apple Menu > "About this Mac..." then click "More info...") shows the machine model as PowerMac6,4 the eMac will handle 2GB RAM. We have the last eMac from 2005 with a 1.42Ghz processor and it is running a full 2G of RAM. However, you have to get it from a place that recognizes that the 6,4 eMacs can handle more RAM. Crucial does not. I got our RAM from Other World Computing:

1GB PC2700 DDR 333MHz CAS 2.5 184 Pin DIMM

and it works perfectly.

Our eMac also runs OS 10.5 Leopard fine. The secret is the 1.42Ghz models have video hardware that fully supports one of 10.5's key graphics technology. If you have the 1.25Ghz model, it may struggle with 10.5 even if you max out the RAM. If that's the case, stick with Tiger until she needs a newer Mac.

The earlier eMacs have the machine model code PowerMac4,4. These can only manage 1GB RAM and the older processors and slower system buses in these are not very capable any more. There is not much you can do to improve it if it's a 4,4 eMac.

So I think we can't go much farther with recommendations without knowing the details of your mum's eMac. That System Profiler page that has the model code will give us all the info we need. Looks like this:

You can copy down to the line "Bus Speed" and paste it into a reply to any post in this thread. Please DO NOT include the serial number or the the Hardware UUID.

The sample is from a newer Intel Mac but the format is the same in OS 10.4.

As Allan says...

At the Apple Icon at top left>About this Mac, report the version of OSX from that window, then click on More Info, then click on Hardware> and report this upto but not including the Serial#...

Hardware Overview:

Model Name: eMac

Model Identifier: PowerMac6,4

Processor Name: PowerPC G4 (1.2)

Processor Speed: 1.42 GHz

Number Of CPUs: 1

L2 Cache (per CPU): 512 KB

Memory: 2 GB

Bus Speed: 167 MHz

Boot ROM Version: 4.9.2f1

if she has 10.4 and it's running incredibly slow for e-mail upgrading the os won't help. something else is wrong, she shouldn't be having this problem.

Peter wrote:

Also she lives in France and I'm in London - so trying to find time to skip over and do this

I understand! I thought she might be within walking distance so you could pop over for a visit and check the model while there. I was obviously wrong.

Hope you get to see her soon!