Best deal is for biostar 945GC-M4 for about $52.95 at amazon.com or buy.com. But your cpu is old and slow; you might as well change to a newer cpu and ddr3. Best deal is for sempron 140 which will work with either ddr2 or ddr3. Used they go from about $25; new about $37. This is a single core, but one extra core is disabled, and may unlock with the right motherboard. DDR3 is now cheaper than ddr2 depending on where you live. Save your money until you can upgrade the cpu/board/ram at the same time.
ya i think that's the only option left.i am using this system for the past 10 years never had a single problem except slow while playing games. in my place changing motherboard means better buy a new system not much difference.
thank you very much for your advice suggestion.