What specs do you have?
The quickest way to find the type of processor in your iMac: In the Finder, choose About This Mac from the Apple menu. Look at the Processor line to see which kind of processor is in your iMac.
Checking Available Hard Drive Space on Mac OS 10.7 or Later If your iMac is running OS 10.7 or later, from the Apple menu, select About This Mac. Click More Info bar. Click Storage and use the window which appears to check how much hard drive space is available on your iMac.
If your iMac is running Mac OS 10.6 or earlier, check to the available hard drive space as follows: Switch to the Finder, open a new Finder window. From the sidebar, select your hard disk by clicking it once. From the File menu, select Get Info. The window will show the disk space available on your iMac's hard drive.
To find out how much memory (RAM) your iMac has go to the apple menu (top left of your screen) and select About this Mac. You’ll be given a screen that displays your processor speed and how much RAM is installed.
To find the video card installed in your iMac, click on the Apple symbol at the top left of the Mac menu select About This Mac (the first entry), click on the More Info... button at the bottom of the dialog. This brings up System Profiler. Look under the Contents column on the left and find Graphics/Displays under the Hardware section. Click on this, and the details on your graphics subsystem, including vendor, chipset and ROM version, will appear on the right. System Profiler can also be launched from the Utilities folder under Applications.