Upgrading from a 2008 Mac Pro

I need some input from you guys. Here goes:

I'm thinking of upgrading my Early 2008 Quad-Core Xeon Mac Pro (with SSD) with the 2012 27" iMac "top of the line" in december.

In case of performance and everyday use; How will it compare?

I also use my current Mac Pro for quite heavy PSD-files and running Parallels for Windows-applications I need at work.

Thanks!

In addition to PS-performance; will there be a significant overall performance boost, or will I hardly notice it? I know this is highly subjective, but I'll give it a try.