http://www.cpu-upgrade.com/mb-Intel_(chipsets)/945G_Express.html
i would say the chances are not good. Even Gigabyte's GA-945GCM (http://www.gigabyte.com/support-downloads/cpu-support-popup.aspx?pid=2669) only supports those via overclocking, so I wouldn't expect a more "generic" company's board to support them, despite the 1333MHz FSB specification.
The biggest question, of course, is what CPU you currently have in it. The top ones on the supported list were the E6600 & E6700. Compare those on the tier list to your current CPU (http://www.tomshardware.com/reviews/cpu-hierarchy,4312.html); unless it would move you up at least 2 (preferably 3) tiers, it won't really be worth it, especially for such an old platform.
Now, if your...