Further to what Levi said, I think you need to spend a bit more time working on the letters, neither is particularly clear. There are quite a few options
with O and S. Get a pencil and paper and scribble as many ideas as you can think of. If you're struggling, just Google 'OS logo' for a bit of inspiration.
As he works in computers, OS may not be the best thing to choose as a logo, so maybe have a look at just having a name style?