Artweaver is Photoshop and Painter rolled into one fantastic free art program. You can use filters that make your work look like painting masters, choose from a wide range of art supplies and techniques, manipulate items and enhance photos. The only downside is that you can't create layers. This art program is available for download on a variety of sites. Simply do a web search for "Artweaver."
Using these free software downloads you will always have the drawing and painting software you need to create digital art.