Most hosting platforms include stat scripts for use by the clients, such as awstats and urchin. We keep logs at the routers and compile numbers once a day.
I've been using Firefox for about three years, and never used IE6. I do admit though that IE7 is beginning to tempt me. Must. Be. Strong.
I have a local manufacture that has machines with hard coded installs of Windows 1.0 on their machines. Folks may not be upgrading for a number of reasons. I know here in the library, anything over 5 megs, I can't download because the proxies in pace disconnect. They do it as a deterrent towards torrent running. (But yet the largest torrent packet is 4 megs....)