Can you be more specific when you say SOHO? Do you need databases, spreadsheets, bookkeeping software? Do you need portability of your files with Windows systems? Will you be running the distribution on a laptop or desktop? Are you a heavy user with large memory demands or with large graphical demands? Most important of all, have you checked distrowatch.com?
Fedora is a cutting edge development distribution. To a certain extent, things are expected to break in it. It is the upstream development release for Red Hat, CentOS, etc. Unless you know what you are doing, I would not recommend you use it. Ubuntu is probably what you should use.
I consider running openSUSE or Ubuntu.
Which one would be the best solution to a novice user in linux and to allow interoperatibility with windows platform ?
I'd recommend OpenSUSE. I never really got into Ubuntu, though I gave it multiple tries. It was just not something I liked. I have used OpenSUSE and SUSE for years now and found it stable and easy to use.
You may find support on any distribution will depend on the specific hardware you're running. Support for laptop hardware on Ubuntu is very good, but unless you're sure the laptop is fully supported, there are no guarantees. I'm a long-time Debian snob, but have converted to Ubuntu for desktops simply because is usually "just works" and I don't have to spend a lot of time talking friends and colleagues through fixes. That doesn't mean other distributions aren't also good, however.
The good news is that there are several excellent distributions to choose from. In the end, linux is linux, and anything you can do with one can be done with the others. You might want to share more details on your hardware in case there are limitations that will steer you to a recommendation for a lighter distribution or specific choices.
Everything should have it's own system. It's a risk management thing. But if this is for your home entertainment/education, try and give the router a system of its own and lump everything else together.