KeyRemp4MacBook, but I don't see how to get it to do what I want
Make sure you have the most recent version. Then look in the section "For PC Users". There's a lot of stuff in there that does exactly what you want. Like "Use PC Style Control+Up/Down/Left/Right", and "Use PC Style Copy/Paste".
Bitt, I should have known better than to doubt you. You were completely correct about this, and I'm extremely happy with the results. The only thing the application didn't have was remapping ctrl+W to close a tab, but I was able to do that in the keyboard preferences.
I'll take a look at Witch. I'm hesitant to spend $14 on such basic utility...