2GB of RAM is considered pretty small by today's standards. It'll run, but you'll be severely limited in how many applications you can have running at one time, how many browser windows at one time, etc.
You don't want to rely on virtual memory. Yes it'll save your bacon in a pinch. But it's slow -- "virtual memory" means "save the overflow on the hard disk". And reload it from the hard disk when you want to access it again (called "swapping"). And back and forth. SLOOOOOOOOOOW doesn't begin to describe the performance hit.
That's true for all virtual memory, BTW, not just Windows.
You can improve the swapping situation somewhat if you're using a solid-state disk (SSD), but you'd be better off getting another 2 or more GB of RAM, than a SSD, at least at first. OTOH, if your computer can only hold 2GB RAM max, then an SSD will improve things over a rotating hard drive.
So the answer I'd give you is, Yes you can upgrade with only 2GB of RAM, but you'll soon wish you had at least 4GB.
Thank you for your reply.
I use my computer to compose long emails and post to Facebook and Twitter. I use my 8.1 phone to do short emails and post to Twitter and FR. I use the computer in the living room to watch t.v. shows on the Samsung. I just miss having the One Drive folders on my desktop, not to mention all my bookmarks are there, although I can access them on my phone. So I really look forward to being able to upgrade and, if Windows 10 will be free, all the better.
Thanks again.