Most multi-project systems are being marketed as "Enterprise" project management systems. There are a lot of systems out there geared to this purpose. I do not have enough experience with them to offer you a recommendation though. I did create a directory of Windows based project management software which you might use to investigate possibilities:
As Bernard says, there are "enterprise systems" out there. I've had a little experience with two as well as FastTracs and MS Project.
Both enterprise systems are geared mor toward accounting than manufacturing or project work. The Bipics system was only as good as its calendar and that had been overrode in so many addons that it was completely ineffective by the time I met it.
The Avante system we now use is better but still limited by calender maintenance. A second issue is whether the system allows individuals to enter work orders or changes in some kind of arbitrary manner.
Either system was capable of backward or forward scheduling but certain types of on-going tasks seemed to create false schedules. We had work that needed to be done periodicly and rather than create a new work order each time, a single wo was kept open in the system indefinitely. Having a number had the effect of showing far past due work and attempting to schedule resources to clear them.
At the risk of making a generality, I'm going to say that there are likely several systems that will do the job but any of them is only as good as and for as long as management's committment to it. This includes maintenance of the system and accountability for the schedules therein.
Sorry about the length of this post but having tools that don't work correctly is a pet peeve.
