Heyyo,
Now, alienware don't only give you a spiffy case n' such, but I'm sure they pre-oc all their comps and then cover that with warranty, so that's plenty sweet.
Now, his old alienware, what kindof CPU does it have eh? I know for AMD I've only seen s939 cpu's with pci-e, I dunno if this applies to intel.. anywho, might wanna check that your cpu is the same socket as that mobo you plan on getting.