To answer you another question "is it worth for me to upgrade CPU and will i see noticeable difference?" It depends on purpose for which you use machine. For daily use (Not CPU intensive tasks), you will not see noticeable difference. If you are using for heavy tasks, like playing games, you might notice some extra FPS.
Well, for the price of new Intel Core 2 Quad Q9650 or a bit more i can find some I7 processor, that would be much more powerful so i started thinking about getting a new mobo, cpu, ram to have some more expenses but much faster machine