Compatible

So my stuff shows up from Newegg, I put the CPU and fan on the Mobo, Put the GPU on, I go to put the memory in ... oops. I forgot to check if my new Mobo was compatible with the memory that I already have. Of course it's not. Back to Newegg. Should get 2x1Gb DDR2-800 via UPS today. At the rate I'm going, getting XP to cooperate is probably going to want to make me kill myself.