Intel Centrino is
Intel® Centrino® processor technology is the brand name for Intel's wireless mobile computing technology. The brand signifies Intel's technology for notebook computers. The technology is based on mobile processor microarchitecture, mainboard chipset, and wireless network capability.
... according to Intel
You don't have an Intel Centrino Duo T9600. You have an Intel Core 2 Duo T9600. No, I'm not nitpicking. You are asking about replacing the processor, and knowing what you have in there is important when you start looking for replacements. Believe it.
There are multiple hurdles to replacing a LAPTOP processor. The largest of which is whether the laptop manufacturer wrote a BIOS that will recognize the processor. Why wouldn't they do that, when Desktop manufacturers are constantly releasing BIOS revisions that are only for increased processor support? Economics. Sounds conspiratorial or paranoid, but it isn't. Laptop manufacturers make money by selling laptops. If you can upgrade the hardware to something better, you aren't buying a new laptop and they aren't making their money. To this end, while desktop manufacturers will list what new processors are supported in a BIOS revision, Laptop manufacturers won't. You need to be prepared for that.
If you want to RESEARCH, then you start looking up other Acer laptops in that same series and family, to see what processors were used and if any of them are better. Provided the laptop was made at the same time, and in the same model series, if it is a better processor (same socket, etc) then chances are you can upgrade to it.
At the very least, you are most likely safe within the same series of processor... IE within the T9000 series of processors, which would limit you to the T9900 3.06 dual core.
As to the video card, I've seen video that demonstrates that the 6930G uses an MXM form factor video card, which means it can be replaced and upgraded.. specifically an MXM Type II. You can get more information at MXM Upgrade, a great site for information on this form factor as well as the ability to purchase some cards... however, nothing should stop you from searching Ebay as well. What's the best card you can get for that? I've no idea. MXM, although a standardized form factor, still proves to be touchy. For a related example, the ATI Radeon HD4670 worked, but with issues, in the Acer 6920G. It was an MXM-II card, being used in an MXM slot on a system that accepted and worked with MXM-II cards, yet it would not work properly. Once you find a card or two you like... or if you just feel like getting specific recommendations, you should contact the people behind the site MXM Upgrade.
That covers the scope of your question that can be answered here. Shopping recommendations are off-topic and will get your question closed.