Calendar Sharing with OUtlook 97

At present use OUtlook 97 calendars with all technicians. We do not use exchange at present. Is there any way on a NT network to share these calendars amongst our own dept.? FOr instance I know under the old MS mail 1-7.0 you have a post office and can look at each others calendars. With exchange you can do the same. At present someone else has our mail server and calendaring is held on each PC. Any ideas or cheap software that wouldn’t interfere with present mail server and still allow us to see calendars for each other?