Here is a fascinating motherboard (IMO) - supports DDR2 and DDR3 - I'm sure not at the same time though. It's AM3+ so it has potential for upgrades I think it's kinda cool, it's not expensive, I think it could work for your needs (which I'm judging by the original board you had).
ASRock N68C-GS FX AM3+ http://www.newegg.com/Product/Product.aspx?Item=N82E168...
The only issue I can see is that you only have 2 ram slots for either type of memory so if you have 4 DDR2 modules, two would have to be left out
hope it helped