So, I've been using the standard mouse, and have had friends telling me for years that trackball is the way to go.

If you ever converted to a trackball from a mouse, and stuck with it, what about it did you like most? I'm sure the whole not needing extra desk space is nice - anything else?

I was a trackball guy years ago- back when mouse balls were always dirty and cords would get tangled.  Then came the wireless optical mice and a scroll wheel that does up/down and sideways.  Side-scrolling in a music or video program is really nice.  It also has buttons that do forward/back in the web browser. 

I notice people that complain about the mouse usually have it set to the stock sensitivity and move their arm and wrist all around their mouse pad.  I set mine pretty high so I barely even need to move my wrist- mostly just fingers.

I use a trackball with my laptop/traveling ";rig"; and an optical wireless mouse with my desktop.  I would say I like the trackball a little better than the mouse.  I got the trackball for my laptop b/c I was tired of using the mouse pad.  The biggest advantage the trackball is comfort; but I'm sure that has a lot to do with the model: [url=http://www.amazon.com/Microsoft-D68-00007-Trackball-Explorer/dp/B00005853Z]Microsoft Trackball Explorer.[/url]  I don't think they make this one anymore, but Logitech has a [url=http://www.amazon.com/Logitech-Cordless-Optical-Trackman-USB/dp/B00006B9CR/ref=dp_cp_ob_e_title_1]similar model.[/url]  For what it's worth, I've used other types of trackballs over the years like the one with the [url=http://www.amazon.com/Logitech-Trackman-Wheel-Optical-Silver/dp/B00005NIMJ/ref=pd_cp_e_2]";thumb"; trackball[/url] and some of the [url=http://www.amazon.com/Kensington-Expert-Optical-Trackball-64325/dp/B00009KH63/ref=sr_1_3?ie=UTF8&s=electronics&qid=1251649873&sr=1-3]Kensington models,[/url] but I couldn't train my hand to work the thumb trackball very well, and the Kensington wasn't very comfortable - although there are people out there who use them and swear by them.  And I'm sure there are also some very comfortable mice (mouses?) out there.  I would suggest going to a Best Buy/Office Depot store and placing your hand on the different models to see which one you like the best.

Hope this helps....