*Apple officially supports 4 GB of RAM, but third-parties have been able to upgrade the system to 6 GB of RAM using one 2 GB and one 4 GB memory module.
Your processor is a ZIF socket and can be upgraded to a 3.06 GHz
You have a 3 Gb/s BUS so your hard drive can be upgraded. Consider a SSD drive.
In all I would say that you have the wrong machine. Take a look at the Mac Pro Models. These would serve your needs much better than an iMac. The Geekbench on your machine is 3833/4284* *These Geekbench 2 benchmarks are in 32-bit and 64-bit modes, respectively. For example, my Early 2009 Mac Pro dual Intel Xeon X5570 has four hard drives, RAID card, three video cards and 32 GIGS of RAM and a Geekbench of 15548. This machine is right at 4 times faster than your current machine and the 5th fastest Mac ever. The base machine can be had for about $3000 and you can dump all the money you want into it. The Mac Pros were made for professionals while the iMacs are basically entry level machines. A Mac Pro (Mid 2012)Intel Xeon X5675 3070 MHz (12 cores) benches at 22167. Take a look at the new machines here: http://store.apple.com/us/browse/home/shop_mac/family/mac_pro