I have a G41MT-ES2L with an E6500 in it running home office stuff.
This should be your first stop.
Core2 Overclocking Guidehttp://www.tomshardware.com/forum/259899-29-core-overclocking-guide
Shadow's Gigabyte motherboard OC guide:http://www.tomshardware.co.uk/forum/page-245679_11_0.html
It's for an EP35-DS3L but all the Gigabyte Core2 BIOS's are similar. The G41 will have fewer settings.
Go through the guides. Then take your core voltage off Auto and set your memory voltage to factory recommended values You can push the DDR3 voltage to 1.65 volts in a Core2 system. Change the System Memory Multiplier from AUTO to 4.0. Then when you increase the FSB, the memory clock will rise in in proportion with it. At an FSB of 266 MHz, your memory clock should be at 1066 MHz. At an FSB of 333 MHz, your memory clock should be at 1333 MHz.
Download CPU-Z to check your FSB:RAM ratio. It should be a 1:1 ratio.
Here are links to 3 of my replies to G41 overclocking threads (I get tired of writing the same thing over and over
G41 OC threads:http://www.tomshardware.co.uk/forum/267717-11-e7500http://www.tomshardware.co.uk/forum/268217-11-overclock-e8600-helphttp://www.tomshardware.co.uk/forum/268254-11-having-trouble-overclocking-e6400