I used to get sore from typing, until I finally got myself set up correctly ergonomically with everything at the right angle and height. Now I can type all day and all night with no problems! The book I used as a reference is Zap How Your Computer Can Hurt You and What You Can Do About It (http://half.ebay.com/cat/buy/prod.cgi?cpid=271745) which is excellent and I highly recommend it.

I do very strongly urge you to attack these ergonomic issues and fix them! Repetitive stress injuries such as tendinitis are serious and can lead to lifelong disability. There are a lot of things where we can be like, "I'm young and healthy and things don't need to be perfect, I can just tough my way through them". This is not one of them! This is a big deal.

I hope this helps,