Avoiding carpal tunnel / repetitive stress injuries
tortilla: 1) Get a mouse that's flexible enough to use with either your left or right hand. It might feel weird at first, but switching sides every hour will reduce a lot the pain. Takes a bit to get used to but you'll eventually adjust.2) Try to use the keyboard as much as possible for everything. Go into your Keyboard & Mouse settings and enable full keyboard access (or ^fn F7 to toggle on/off)3) Use either Firefox/Camino for you main browsing because you can enable "find as you type" which you can use to navigate the links on a web page.4) Take regular/breaks.  I use http://tech.inhelsinki.nl/antirsi/ to remind me at set intervals.5) Exercise regularly (running, walking, golf, something to get you away from you computer).6) Meditate, relax, listen to music. Whenever I feel like I'm tired or overstressed, I listen to this for about 20 minutes. I'll feel refreshed and much more focused. 
http://www.pzizz.com/ (Energizer track)