I have a 2008 iMac OSX 10.8.5 30.6 GHz Intel Core 2 Duo Processor with 4 GB 800 MHz DDR2 SDRAM Memory and 1T HD

I have a 24" Early 2008 iMac OSX 10.8.5 ...30.6 GHz Intel Core 2 Duo Processor with 4 GB 800 MHz DDR2 SDRAM Memory and 1T HD. Can I upgrade processor speed and if so to what. Can I upgrade memory and if so to what. I run iPhoto '08 7.14. Any input would be great. Thanks for your help and suggestions.