Depending on your year and model iMac, this may not be a good choice to do.
Some older IMac models can only take from 2- 4 GBs of RAM. With only 4 GBs of RAM your iMac WILL feel a lot more sluggish as the newer versions of OS X ( OS X 10.7, 10.8 and the upcoming 10.9 ) use more computer resources like CPU, GPU and RAM just for the running of the OS, alone! You running other applications along with the OS and things will definitely start feeling slow and sluggish.
You'll have to weigh that out the possibilty with updating your OS X version just to be able to "connect and store data to the cloud" (which is just a stupid metaphor, IMO, of saying you're storing your data to remote network servers somewhere else in the country), that you maybe slowing down your iMac's overall performance by doing so.
I, personally, have no interest of storing all of my personal and privatd data to some unknown and random network server farm.
Personally, I think this Cloud Conputing thing/fad is just another way of gaining and controlling more peoples’/users’ personal computing data/information and tracking computing habits and online activities.