XPS no power problem

Question

I read in a previous problem/solution about replacing the motherboard to fix no power (w/good ac and batt) on the dell xps. I have the same problem, on a first gen XPS. Now, is this THE only possible cause for this or are there other things that could be the root problem? Also, where would I get a new motherboard--through dell? I couldn't find it listed on their website. What's one of those going to cost, about? Is it something that I could replace easily by myself (I have a little experience switching out things, but never a laptop motherboard!)?

Thanks,
Ryan