iMac running rather slowly?

Hi everyone,

My iMac has to be the best computer I've ever owned. I bought it in 2008 and it has given me little to no trouble at all. However, over the last year or so, it's started to slow down. I realize it is about six years old now, so that could be the culprit. However, when I bought it I tried ot make sure it had the best of everything.

It's OS X 10.5.8. The processor is the 3.06 GHz Intel Core 2 Duo with 4 GB 800 MhZ DDR SDRAM memory. The only game I've purchased is The Sims 3. I do have quite a bit of music on here but no movies ot my knowledge as I know those can slow things down fast. Most of what I have on here are a few papers from my graduate program and maybe a few PDF downloads of articles i had to read for it.

When I open up system memory on the activity monitor, it says I have 2.20 GB free, 599.83 MB wired, 793.10 MB active, 447.53 MB inactive and 1.80 GB used. When I open up disk usage on the activity monitor, it says 81.63 GB is utilized and 616.69 GB is free.

I am not a computer guru (I'm the "computer genius" in my family because I know how to alternate windows and create new tabs, if that gives you an idea of how advanced my family is) so I'm not sure what this info means to you all but thought I might offer it any way.

Do you all have any thoughts? There seems to be quite a bit of space left on here to my naive eyes, but I'm not sure if that has anything to do with a computer running slowly. I just am wondering if it's time to invest in a new computer or if it's running slowly because there's something else causing trouble that I can easily remedy. I'm hoping for the latter--this has been a lovely computer and I'd had to part with it.