I don't think xcom3 was able to run in dosbox... You'll have to get VDMSound for the sound issues and download a few fixes from here :
www.xcomufo.com
for more problems you can also check out the forums over there
Phoenix-D : there also is a fix for the CE Version that will disable/enable directdraw automatically for you when you run xcom. Makes life easier
[ December 24, 2003, 10:45: Message edited by: ace joh ]