If building a computer, I'd go all SSD other than your external backup drives (which should never be connected unless doing a copy.) That way, if your machine is running while on the road, data losses from a disk crash are minimized... but SSDs are not that reliable, so having a backup is still critical.
Don't discount laptops entirely. A Dell Latitude E6440 or something similar can boot Windows Server 2012 R2 in 3 seconds, especially if it has a decent SSD. Unless you are running the latest version of Crysis at full settings, the video is decent enough for gaming. It won't be as good as a desktop gaming rig, but it will definitely take up far less space.
Remember: Get the Latitude or business line. Not the home/consumer lines. Big difference in tier of service and such.