Karmic Koala (9.10) only lasted overnight. It broke my wireless again, and a few other minor things.
Lucid Lynx (10.04) is Ubuntu's latest and greatest (for now). Wireless is back. Not many issues that I didn't already have. Wine 1.2† is no better than it was, despite the hype. Some Firefox 3.6.7 plugins do not play well with others.
Mostly satisfied. The basic Linux part of my Dell Inspiron 1525 is now very nice.
Firefox 3.6.7, not actually part of Lucid, is almost unusable without AdBlock Plus and NoScript; both of these have a learning curve.
Also, the screensaver comes in Lock mode by default — you have to go to System → Preferences → Screensaver and turn it off. You can still Lock your screen manually using the User item on the menubar.
†Neither SmartGo for Windows nor Many Faces of Go v12 can draw a drop shadow properly using Wine 1.2.