http://www.ntcompatible.com/clist-All-j-All-40.html
theres a lot of useful info on whether a game works on here, but of course thats before you buy it, sometimes there are tips to get it working too, but usually just yays or nays.
also try dosbox for really really old dos games
http://dosbox.sourceforge.net/news.php?show_news=1
http://sourceforge.net/projects/vdmsound/ for sound
The only good way is make a win98 partition and use that, some games just won't behave under NT thats the penalty you pay for having a better OS.
its possible to boot win98 from a CD i've seen.
http://www.heise.de/ct/english/99/11/206/
VirtualPC might work ok, but itll have issues too.