The i5-750 (and the i7-860/870) both utilize an onboard memory controller... so it's not really up to the board manufactures to decide what type of memory to use. Intel says you're using DDR3 and that's that. Anyways, DDR2 prices have been climbing dramatically lately so unless you already have a stash of DDR2 this shouldn't be a problem.
I picked up an Asus Maximus Gene III for $185 from www.ewiz.com (they were real slow to ship, but that was $15 less than NewEgg) That's considered a high-end board, but that's what I wanted so that's what I got. I generally prefer ASUS so here's a list of Asus boards that'll work with that i5 you're lusting after...http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&DEPA=0&Order=BESTMATCH&Description=asus+p55&x=0&y=0