I have an old iMac 2.4Ghz, Intel Core 2 Duo. I bought it new in 2009 I think. It works fine but I'd like to upgrade it to a new operating system. Right now the most it can have is OS 10.6.8. I have a brand new iMac for home use. I work in a church and we don't have money for a new computer so I'm trying to get this one up and running for writing sermons, email, and the Internet. Suggestions? Do I need to get an external hard drive? etc.?