A lengthy preamble:

One of my computers dual-boots Linux Mint and Windows 7. Almost the only reason I use Windows is for running the Simply Accounting program.

Recently I inherited a second computer running Windows 7, and after installing Linux Mint, installed Simply Accounting on the Windows partition. Although at that point I was uncertain whether I really needed another computer, I was thinking this might be a convenient way to have multiple backups.

I was unhappy to discover that the new installation of SA would not open my back-up files. Visiting SA forums, this apparently is not an uncommon problem, and I still hope to sort it out. In the short term I have downloaded all the important SA information as a succession of reports in PDF format, and my original installation is still working fine.

So, the question: this left me wondering whether—given the number of times I have installed operating systems from an ISO image—whether it is possible to make an ISO image of my system (or something similar) and transfer it to another hard drive.

My first thought is that the Windows program would rebel if it ever had a chance to call home. . .but my Windows partitions never go on line. In any case, if I had a duplicate hard drive, I would probably put it away in the safe as a just in case.

Any comments?

Can I make a copy of an existing operating system? yes it is called cloning.

if you just want a back up of Windows so that your SA will still (hopefully) work with your original SA files. then search for "free" cloning Software or buy some, I picked up a copy at BestBuy that included a cable USB to SATA to clone Windows to another HardDrive. it was like 30 bucks I think, I got it on sale.

To run a single application I'd consider Windows in VirtualBox. You can transfer the virtual machine image into another computer and it will run.

dd can be very destructive if not used carefully but that is what i would use if i had an identical blank hard drive.

I don't recommend cloning usually. You never know what you have to begin with. If you create a known new system then I'd clone it for golden image.
So, yes as noted above you could clone the entire drive. There are many ways to do that from free tools to commercial products.

However I'll have to point out that cloning is a good way to return a system to the exact same system but even then it may fail. Windows is the worst but you'll find linux can be a real stinker to go from machine to machine. You may find it difficult to clone a windows to some other machine.

Someone brought up a vm. You may be able to use a P2V application and create a vm that is slightly portable.

Programs like Acronis can make copies and might be able to take windows from machine to machine.

I use G4U on some very difficult to clone systems only because they are so old and an odd OS.

the major problem what the OP is experiencing the software on the windows only working on original install of said software, that is my understanding to why they want to clone that original OS so that if needed they have a back up so that that same SA software will still be able to use the files, whereas another install of it does not.

could you grab your program files from C:\ program files and put it in the same spot on the new install?

I vote wholeheartedly for this solution, having done things like this both ways, VirtualBox is an infinitely more painless and time-efficient alternative.

Okay, all the above gives me starting points.
I'll call this solved.