I actually decided to bite the bullet and go for it.
I'm sitting at my MAME PC right now with Windows 7 64-bit and an ArcadeVGA 3000 installed.
The ArcadeVGA has 64-bit drivers now. In fact, it even has drivers that work on XP 64-bit.
I'm doing a little tweaking right now with it hooked up to my PC monitor (LCD) but when I'm done, I'll connect it up to my arcade monitor and give it a workout.
GroovyMAME support forum on BYOAC