From what I can tell that MB only supports up to 95W CPUs. This limits your options quite a bit.
Throttlestop requires an unlocked CPU and your only option is a Q6800 dual core 2.93GHz. All the others are 130W CPUs.
There are a couple pinmods using tape to raise the fsb from 266 to 333. E7400,E7500 2 cores (3.5GHz,3.66GHz) or the old Q6600 GO to 3GHz.
The Q9550 SLAN4 C0 stepping is the fastest CPU and performs better than the Q6600 3GHz mod. Probably the best option.
You can try SetFSB software (the older free version). You need to know your PLL chip to use it. It raises fsb, and RAM speed also but without extra Voltage results are usually very limited.
if your programs don't use more than 2 cores the pinmod 2 core is good.
There is a more advanced pinmod to raise Voltage called the VID mod. But it varies from one CPU to another so there's no simple recipe for how to do it.
The locked BIOS, low power limit, and CPU stepping fussiness all conspire against you.
http://www.cpu-upgrade.com/mb-ECS/G43T-M(V1.0A).html
E8600 2 core 3.33GHz , and Q9550 SLAN4 2.83GHz are your best options.