That was what I was eluding to, but I did not want to give anymore details because I think it is such a terrible way of keeping notes to yourself (to make up graphics where you make a .BMP of yours notes). By the way, you do not need for them to be .BMP (unless you are using Win98 or less). WinXP can handle other graphic formats as well.
But since you have brought it up, I guess it doesn't hurt to give you a pointer or two. If you are using WinXP, you can use the "My Pictures Slideshow" screen saver. With that you can put your images (the text saved as a graphic image) into any folder you want. Just only use those images that you want to appear as a screen saver in that folder). Then, change the [Settings], Use the pictures in this folder" selection to point to that folder.
However, I think this is a terrible way of keeping notes to yourself. I would rather spend an hour of searching for the correct freeware of doing what you want, than just 10 minutes of making "text images" for notes. The notes created that way will not be editable. Any changes and you will have to recreate the images again. And every update will be another time spent in making new images. Just way too clumsy.