64-bit apps need 64-bit plug-ins. In theory, anyway. So anything that's missing, you probably only have in 32-bit form.
There are 64-bit versions of most/all of the NewBlue plug-ins I have, so those haven't been a problem.
And I think a good deal of the random VST plug-ins I have show up, even though they're not 64-bit... or I didn't think they were. I'll have to check on that in more detail.
Weldon, the MSP package is 32-bit only because it came bundled with Vegas Movie Studio which is 32-bit only. So the MSP package will not show up in the 64-bit version of Vegas. However, all NewBlue retail products will work with the 64-bit version of Vegas.
As for other plugins, scripts such as Excalibur, Ultimate S, etc... will all also work in the 64-bit version of Vegas.
But you can run V10(32) under W7(64), render the relevant bits, and swap the files/events back and forwards, as a workaround, if you really need a particular 32-bit plugin for something.