It worked. Powered preview image files, and doc. odt, xls. Does not work I have txt files. I use OpenKM 5.0 bulid 3361.
# Default configuration values
#repository.config=repository.xml
#repository.home=repository
#system.user=system
#default.admin.role=AdminRol
#principal.adapter=com.openkm.core.UsersRolesPrincipalAdapter
#max.file.size=5
#max.search.results=25
#system.demo=off
restrict.file.mime=off
restrict.file.extension=*~,*.bak,._*
#system.ocr=/usr/bin/tesseract
system.openoffice=C:/Program Files/OpenOffice
system.img2pdf=C:/Program Files/SwfTools/jpeg2swf.exe
system.pdf2swf=C:/Program Files/SwfTools/pdf2swf.exe
schedule.mail.importer=1
#hibernate.dialect=org.hibernate.dialect.MySQL5Dialect
hibernate.dialect=org.hibernate.dialect.HSQLDialect
hibernate.hbm2ddl=none
application.url=http://localhost:8080/OpenKM/com.openkm.frontend.Main/index.jsp
max.file.size=060520010
#principal.adapter=com.openkm.principal.DatabasePrincipalAdapter
#notify.twitter.user=openkm
#notify.twitter.password=****
#subscription.message.body=Prueba.vm
wizard.property.groups=okg:consulting,okg:technology
wizard.keywords=on
wizard.categories=on
logo.login=C:/jboss-4.2.3.GA/my_login.gif
system.img2pdf=C:/Program Files/ImageMagick-6.6.5-Q16/convert.exe