My choices were to suck it up and accept the skipping and chattering whenever I pedaled with more than gentle force, or use the biggest gears and smallest gears, as they didn't chatter, but that worked up to more cross-chaining than I really wanted to do.
And I immediately started thinking the worst- that every little skip and chatter of the new chain would immediately screw it up so that when I got home and switched back to the new 8-speed cassette the new chain would be totally ruined and I'd be compelled to start new again.
So I got home before my mind exploded from the painful thought exercise. I'd gone ten miles on the new chain/old cassette combination, and immediately (8:15 in the morning) took off the old cassette and put on the new one again. I don't plan on riding a "healthy wellness" ride today at work (It's supposed to rain, and I'm a wimp), but I will tomorrow, since it's due to be sunny and warm-ish.
Thus, my weekend bike ride efforts were truncated, but happily it turns out that I had ridden just enough to keep the bike riding ahead of the car commuting: 423 minutes vs. 421 minutes. This was primarily on the strength of a two-hour and sixteen minute ride on Saturday morning, where I covered just over 34 miles. It started out near freezing, but warmed up to about 45 degrees as I enjoyed the country roads of Spotsylvania and Caroline Counties. Plus, I found three pennies in an intersection.