Would not advise having a 32-bit OS and 64-bit Vista OS install as dual-boot. Files are different for both versions, and ancillary programming also is different.
Best would be the compatible 32-/64-bit version.
The 64-bit version would overwrite those programming files which the 32-bit OS uses.. and render the install useless.
Stanford obviously is formulating the F@H process for optimal use with Vista 64-bit OS versions. Should be a Beta version available soon that will take advantage of the 64-bit properties. There already is a Linux 64-bit version.
All the OS versions for F@H can be found here..
http://folding.stanford.edu/English/Download
You can easily set up the F@H program as multiple threads with dual-core or quad-core CPUs.. and not have any problems, as long as each process is in a unique folder of its own.. with a control line specifically to that folder.
Some users can assign a priority core for each F@H process.. but if the routines are quite different in execution, it may cause one core to run hotter than the other.. leading to stability problems. Best to let the OS distribute the threading 'as required' so all cores are equally active.
F@H.. to solve mankind's maladies.. in our lifetimes!