Question:
Once my machine has an empty primary partition
and i install win32 into that partition, i expect that win32's bootloader will then obscure the
existing boot manager that was acting in my second Linux partition
(partition 2 "tinyCORE" Linux--)(logical partition)-- syslinux boot manager.
My experience is the same, best to install a Microsoft OS first. However, if your system has the luxury of a second physical drive, uses a good old fashioned BIOS and you have access to the hardware then the solution is simple and it does not matter which OS gets installed first/last/re-installed.
For example, install Linux distros onto SDA, temporarily disconnect drive and install Windows OS onto 'SDB'. Reconnect both drives and set the BIOS to boot from SDA, where the Linux bootloader resides. With a bootloader like Grub2, running an update-grub will then auto find the Windows OS and add it to the boot list.
With this technique subsequent Microsoft re-installs won't wipe out bootloader. Probably other methods, although this one is bullet proof and doesn't require re-installing Linux distributions and bootloaders just because of a Microsoft issue.