From someone who has tried to create a duplicate computer in the past I will tell you all the issues you are likely to face.
The easiest way to duplicate a system that is complex and has lots of plugins is to use something like Acronis Universal Restore to make an identical copy of the OS and all of it’s plugins and drives. However, the next computer is likely a laptop and will need all of it’s drivers installed over the top. If you can get most of your plugins on iLok, you can then just move the eLiecenser and iLok from your main computer to your 2nd computer.
However, lots of plugin manufactures only give you a serial number and don’t do iLok. Since the computers, although a clone, will have different hardware and therefore will most likely have a different windows activation and a different hardware ID if the serial is liked to the hardware ID. That means, the serials that work on the first computer won’t work on the 2nd. So you have to get new serial numbers. If the number of plugins using a serial is minimal, this is not such a big deal but it can sometimes mean buying multiple licenses for the same plugin which can get expensive. Now lots of manufactures are moving to online activations and away from iLoks so this is not so easy to do anymore as it was once in the past.
Then every time you install a plugin or sample library on one computer, you have to do the same on the other. You can’t just keep re-imaging it since you’d have to enter all the new serials and install the new drivers again. This becomes a pain in the ass.
My present solution for portability, which I think is the best option, is just to have a super powerful massive pimped out laptop and use that for both in the studio and on the go. It’s one of those huge gaming laptops that can hold multiple internal hard drives. It has huge fans and doesn’t throttle. It’s not so portable because it’s very heavy but it is just as powerful as my old desktop, actually a little faster. Most guys don’t need that much power and hard drive space though and can get away with a smaller laptop. If you do end up buying a fancy laptop sometime in the future, get one with Thunderbolt so you can use Thunderbolt interfaces and old firewire ones. That means you can pretty much take it to any studio and hook it up to whatever interface they have rather than having to bring your own and re-patch everything. I used this to seamlessly move from one studio to another on the other side of the world without any downtime and I use it here in LA to take projects from my studio to home or to another recording studio.