@Anthony Parsons based on the discussion here I would imagine that this older iMac would probably still run circles around a PC that was 1-2 year newer, and to answer your question, yes it is really just for playing around with.
I used to subscribe to getting the latest-and-greatest PC or something like that, meaning I would walk into my local DIY PC store and buy all the parts and assemble myself to use for general use for things like MS office, email, web surfing, as well as AutoCAD and lately some SQL. The heaviest uses I have are AutoCAD and DigDB for Excel. The thing that actually spins up the cooling fan on the processor more than anything else (including AutoCAD, even though it's just LT) is actually Minecraft. Man that program makes the CPU dump out some serious heat.
But lately I just go to this particular refurb store and wait until they get a batch of higher end PCs in, and specific when we went to Windows 7 I got my hands on about a dozen of
these with 8GB ram & quad core for < $200/ea, with Win 7 Pro installed. That was the 2nd round of PCs I got from this store.
Considering that I paid > $500 for my past build-it-yourself PC a few years back, I'll never do that again unless I need to run something like Revit, but even these second-hand PCs run really demanding programs like RISA very efficiently.
The iMac would be used for nothing like this. Minecraft would probably be the most demanding, and that wouldn't be me running it!
Now with all that being said, I used to have a IBM Thinkpad running a Core 2 duo and that thing is a paperweight now, there's no way I would sink anything into it, I just went and got a refurb HP laptop that comparatively screams for ~$250.
So my question is now, if this iMac has a 2.6G Core 2 Duo and 4G RAM, which is 5 year old tech, if this is now loaded up with Mavericks 10.9 (current OS) is that going to compare to what it would be like running that old Thinkpad on Windows 7? Or will this really not be that drastic of a difference on this iMac?