The last few MS wireless keyboards/mice I've used seem to have ridiculously bad range even on full battery. The worst part was it's not consistent. You can be typing a sentence and go back and notice every 5 or 6th letter just isn't there or duplicated. The only way I could get it to work reliability was to have the wireless transceiver practically touching the keyboard itself.
2 other points that are important for RSI/wrist care: keep your wrist in line when you're keyboarding: top of hand in line with top of forearm, and not cocked in towards thumb or out. This means (for me) rolling up a hand towel , put under heels of hands.
Also mind your wrists when you're driving, riding bike, using power tools, stuff like that. It's easy to cock your wrists at bad angles doing all of those and more.
Have you tried the Dynaflex and powerweb exercisers? Also the wrist curl bar
http://www.fitter1.com/Catalog/Category/35/HandWrist.aspx
http://www.amazon.com/GoFit-GF-WFB-Wrist-Forearm-Blaster/dp/...
--------------- giant bookmark dump
http://news.ycombinator.com/item?id=185743
http://www.reddit.com/r/programming/comments/7apqt/ask_progr...
http://stackoverflow.com/questions/687/keyboard-for-programm...
http://stackoverflow.com/questions/288856/best-keyboard-for-...
http://stackoverflow.com/questions/327129/whats-the-best-wir...
http://stackoverflow.com/questions/96944/what-is-the-best-ke...
http://developerlife.com/reviews/?p=46
http://news.ycombinator.com/item?id=199493
http://amarsagoo.blogspot.com/2008/05/science-of-keyboard-de...