Well personally, I have Photoshop CS, Corel Painter, ZBrush 2 (and use bodypaint instead of Deep Paint)... oh and microsoft paint as well! lol! The only thing you need to 'worry' about if installing multiple paint programs, is File associations, which app opens which file type, but that's not a big problem. As for Poser, there are plenty of free utilities for use with poser, uvmapper, MatPoseEdit etc. If you going to be making animations, then a decent Video editor may be useful. Ask in the forum for recommendations (don't forget to mention price) about ease of use or the learning curve.