Why don't you just install the 32-bit version of Vegas (in addition to your 64-bit version) and do your noise reduction from that? There is no reason you can't have both installed in Win7-64.
I too had memory problems with Neat Video's 32bit plug-in. Not so when I went to the 64 bit OS, 64 bit Vegas, and 64 bit plug-in, along with 8 gig of ram. Also, I have not yet encountered the duplicate frame issue but I can say that it works very well as long as it has a nice bland sample area. If it can't find that the New Blue works better.
I do a lot of underwater video so I rely on stabilization and noise reduction to clean up my shots. I use the NR plugs more for getting the floaties out of the water than removing noise.
Comparing New Blue Video Essentials noise reduction to Neat Video: Neat Video does a better job of reducing the noise and the render times are way quicker too. Both really slow your render times. Neat Video is still really slow, but the New Blue noise reducer takes at least twice as long.
There are at least 6 or 7 free video noise reduction plugins for Virtual Dub that I know of. Up until I discovered Neat Video I used the one from Jim Casaburi called "Temporal Cleaner." Now I use Neat Video for all my video noise reduction needs.
I'm glad to hear the 64 bit is more realiable. I still use Magic Bullet which keeps me in 32 bit for now. Hopefully most of the plugins will be upgrading since Adobe is going full 64 on future apps.