What will the performance difference be?

[iBookG4user]

I currently have a 15" MacBook Pro with a 2.0GHz Core Duo, with 2GB of RAM, 80GB 5400 RPM HDD, ATI Radeon X1600 128MB (original underclocked version). I was looking at getting the new MacBook Pro (either 15" or 17" with 1920 x 1200 resolution) with a 2.4GHz Core 2 Duo, with 4GB of RAM (I can get a good price.), 160GB 5400 RPM HDD, NVIDIA GeForce 8600M GT 256MB, and with the 17" the higher resolution display. I was wondering what the speed differences were in the following places.

Adobe Photoshop CS3: using this speedtest. My MacBook Pro gets around 1 minute 20 seconds

Gaming: just general speed differences with the new graphics card

Encoding using VisualHub: just what would the general speed differences would be

Thanks .