If you don't have your desk setup correctly your are going to get RSI which can be incapitating. So here is a number of links, guides that we have found helpful.
By having my desk setup incorrectly I have just given myself 'mouse elbow' so it is
The Ergotron workspace planner is great and gives you an easy to use diagram with all the heights marked on it:
Chair height 48
The UCLA Office Ergonomics was very practical but missed for me the adjustment of the table height.
Having made the adjustements in height and also using an Anker Vertical Mouse I think my elbow is improving.