Ive been using VistaStartmenu almost since i started using stardock...
It does the job, though i would still prefer a complete replacement of the 'windows' start menu' still.
As far as 64bit veruss 32bit..
On my 64bit quadcore vista64 system with 6gig, I have a huge amount of 32bit and older applications running and much of it with no customization at all...
I even have some old windows 3.1 still... and even older stuff in some cases.
Naturally when I find a better version of a application or etc, i replace it, but I tend to retain all my past stuff on cd's.
I have had every version of OFFICE since the beginning, but run the latest when possible.
In the startmenu issue, its more about stardock laziness or incapability especially when you can google the alternatives and try each one out.
I tried several and chose the one I liked most. and though I have to still retain the 'original' windows taskbar still, its getting me there.
The only thing keeping me from hiding the windows task bar totally, is the rightmost task items are not showing in stardock when active apps do.