AutoCAD2000 again and CreateFiber

[Max]

Well, after the patch-hack-or whatever on VirtualQuery, AutoCAD2000 began 
coming alive ! Some problems yet, but one wonders me in particular :
setting window version as win98 or winnt40, app shows an exception stating 
that CreateFiber function is not implemented; setting as win95 the apps 
starts quite well.
Any idea ? Is there some plan to implement xxxxxFiber functions, or it's too 
difficult ?
BTW, looking for help on the net, i haven't really understood the difference 
between a regular thread and a fiber (only caught that use of fibers instead 
of threads is somehow discouraged...)

Regards

Max