I've been a user of Linux on the desktop off and on again over the years. I very nearly switched my primary computer to Ubuntu prior to the release of Windows 7. There were a few, but significant issues at the time that prevented wholesale adoption, mostly tethering with my phone and lousy VPN Client.
One key component I could count on was the Accessibility features. I have recently installed Ubuntu 10.10 and am considering giving it another try, but it appears Ubuntu has taken a leap backwards in that it no longer has a click lock feature for the mouse.
Basically I need the ability to press and hold the left button to trigger a locking of the button so I can move the mouse by way of a trackpoint with my prosthesis. I absolutely require this feature and it is a deal breaker if it won't work. I've tried the Dwell keys but this is a chaotic control at best. I've never been able to manage a drag of any kind.