I think I might have solved the problems I'm having with my 64-bit Vista laptop and my wireless connection. As I mentioned before, I tried an experiment: I hooked another router to the FIOS-provided Actiontec router. It seemed to improve things, but I was still having problems.
On Friday night, I tried something: I switched the security on the Actiontec router from WEP to WPA. Since then, I have had no problem at all. Still, I'm not going to celebrate just yet: let's give it a few more days before I declare victory. By the way, remember that I said that I was having no problems with any other wireless connection? It dawned on me: none of the other routers used WEP either.
I am wondering: has anyone else out there encountered this? 64-bit Vista systems and WEP wireless connections?