A pop up occured in March that said I had need of spy ware. I thought
it came thru google, but my email must have been open as well. I just
got another pop up of the same kind that said my computer could have
been invaded and that i should run spyware. I was afraid to run it
because I thought it might be some kind of hoax, but recently the date
on my emails reverted to January 1970. So now I think I need some kind
of detection. Can you advise me? I have an iMac 10.2.8. Thanks!

Spybot Search & Destroy is really good but I would also recommend that
you get ad-aware 6.  I think both are free at Downloads.com

Good luck

Do not believe various Popups. There are quite a lot of pop up
advertisements meant to push products. these are usually false
advertisements.
Scan your system with free spyware removers: ad aware or spybot. They
remove quite a lot of parasites for free too.
Also you can use any other program which is partially free. For
example  Bazooka (its just free scanner) or Spyhunter (It will scan
your system for free, but you will need to pay for removal).
After scaning you can see what kind of parasites program identifies.
Then you can try to remove parasites manually by using sites which
explains how to remove. For example:
http://www.2-spyware.com
http://www.spywareguide.com
http://www.kephyr.com

know your system and do not believe agressive popup ads.