No, neither XP x64 nor Vista x64 has a 16-bit subsystem. Therefore, any 16-bit applications you have or 32-bit installers with 16-bit components won't work. If you have a 16-bit app you REALLY need to run, I'd try running it in VirtualPC, which is free to download and use. As luck would have it, Virtual PC 2007 RTMs today!
[update] I just found out the Virtual PC 2007 RTM is actually 2/19/07. Sorry for the confusion.
Brian