Upgrade E7200 to Q9550

Hi guys,  

I have a Dell Slim Tow 540SN desktop with ACPIx86-based, Intel Core 2 Duo (E7200) @2.53GHz, 4GB of RAM and ATI Radeon™ HD 3450. I start to do a little bit of HD video editing using CyberLink PowerDirctor video editor. I do some HD video converting with AVS video converter too. My wife took a lot of HD videos throughout my girls’ soccer practices and games. I am editing it to remove all the un-wanted videos and combine the rest of videos to fit in a single blu-ray disc. The editing and converting processes seem to be very slow.  I cannot watch blu-ray while running the video converter either. 

I’m interesting in Intel Q9550 (Quad-Core). Have anyone replace E7200 with Q9550? How much faster is it? I want to make sure it will works in 540SN before I order it. It is too much hassle to return it.

Thanks.