I was going to buy a laptop(XPS 15 is what I've decided on ,since they have only Intel Graphics Card in Inspiron).
I am not sure of which processor I want in it.
The laptop is for Internet,Videos,Images,Programming(in Java,C,C++ ..),Web Development,Video editing(using softwares like Sony Vegas),Image Editing(using Photoshop and the like),Audio Recording and Editing(using Audacity),and maybe a game like FIFA 12.
I going to have 8GB of RAM in it.
I have to choose between :
i5 2450M (2 cores ,2.5 GHz with turbo boost)
i7 2670qM(4 cores ,2.2 GHz)
i7 2760qM(4 cores, 2.4 GHz)
i7 2860qM(4 cores,2.5 GHz)
Ofcourse there are many differences.
Which might suit my purpose?
People say i7 is for CPU intensive use. What is CPU intensive use?
Any examples? Will I need a quad core for my purpose?
CPU intensive use is stuff like programming and media editing (of any kind), so yeah, I'd say one of the i7's is right for you. Which one is up to you, but I'd recommend the 2760qm (the extra 100Mhz with the 2860 won't make much of a difference).
I have a similar laptop (actually the slightly bigger Dell XPS 17) and have a similar usage profile as you, with the exception that I do not program.
I do a lot of photo and video editing and for this purpose, I decided to get the quad core i7 2630QM.
Although a dual core will run all those apps reasonably well, my experience is that video editing with a dual core is a frustrating experience. (My experience with this is a Sony Vaio Z laptop with a dual core i7). The reason isn't so much due to rendering time (arguably it isn't so important whether you have to wait 60 or 90 minutes for a video to render), but real time editing. When you're editing a high definition stream and have several layers of effects, you need ALL the CPU power you can lay your hands on. Previewing your creation with a dual is likely to lead to stutter, which makes it utterly useless. This is where the Quad i7 really shines.
With Windows 7 RAM rarely goes unused. i5/i7 can both make good use of 8GB RAM - especially in a multi-tasking environment. It helps having programs files / data pulled from RAM and skip pulling them off the very slow hard drive.