Some types of viruses, such as those written in a high-level language such as Java, MS Word scripting language, Excel macros, etc, will be able to perform some tricks on a NT machine as well.
According to DR Solomon, the MS Word based concept virus spread widely in part because several companies, including Microsoft, have shipped CD-ROMs containing the virus.
Windows NT machines can be affected by other types of viruses if you use, for example, dual boot to run some other type of operating system on the same hardware, e.g. OS/2, UNIX or other version of Windows. When using a coexisting, bootable operating system, if you have a virus in effect that destroy the boot sector or something like that, your NT partition will probably be destroyed as well.