We cannot compare the Intel® Core™2 Extreme Processor QX9300 with an Core i5 CPU. They have different architecture and also the Sockets Supported are different. In this case, you may need to confirm the compatibility (CPU and motherboard) first with the system manufacturer . They will be able to provide you a list of compatible processors for this system. If they confirm a specific model, you will be able to find and compare the specifications and details at:
i5 is a dual core compared to QX9300 that is a quadcore. I suggest you take i7-2670qm; it's a very good quadcore cpu. I suggest you go and see what clevo has to offer. sagernotebook.com is a good and mostly cheap site. I also suggest AMD as gpu since they are cheaper for (mor or less) same performance. The specific model would be Firepro 5900 or 8900M.
Here is a good laptop for a good price (to good to be true if you ask me...): http://www.merkamericaco.com/dell-precision-mobile-workstation-m6600-intel-core-i7-2920xm-extreme-quad-core-2-50ghz-16gb-1333mhz-250gb-hd-amd-firepro-m8900-2gb-17-3-in-ultrasharp-fhd-1920x1080-wv-led-8x-dvdrw-windows-7-pro-64-bit-silver/
I hope this helps