OTOH, I can understand wanting an "open" tool for this. As much as I love OneNote, it's hard to use on Linux and I do feel the "lock in". There is a browser version of OneNote that can generally get the job done, but it's not as nice as the real app. I just bought Crossover Office, so we'll see how well I can get it running there.
My most recent attempt for going open with note taking is a tool called Tagspaces. It will run on all major platforms and you can put whatever files into it that you want: text, html, pics, etc. Then you can add "tags" to it to mark what it's for. It has search. It can show the file with a native app, or for simple apps show it in the tool and allow you to edit it. Combine that with a syncing tool like Dropbox and I think it will be what I want, or it will be when the next version comes out I believe (I need 1 more feature to make the syncing better, but if you don't need to sync between multiple computers then you won't have my problem). If I can get Tagspaces whipped into shape, then I'll migrate from OneNote to this.