So I have an Alienware X51 Extreme (Is what they used to go by, unable to find them anymore.) And I want to switch it out to an ATX motherboard, for ease of working with the motherboard and swapping in parts, the problem is, I don't want to start transferring, and then not have a working computer. So I was wondering if there is anyplace I could start by getting a case that could hold the Mini ITX motherboard the PC comes with, and then replace that with an ATX when I can save up the money for it, (In the same case). Also what would I need to upgrade/replace for this build to work properly. Thank you for all feedback!