Thank you, David, for your advice. We had been updating straight from our .pln files to avoid .pmks--they used to do that before I started working at my firm and it had resulted in tons of .pmks in our network (resulting in, "which one is the current one?") I had AutoCAD & Microstation experience before this.
Yes, our Teamwork files are huge, and our plotmaker files, linking directly to .pln files, are also huge. One file, we managed to shave down to 100 megs from 150. But that's still quite large!
I'm hoping our upcoming switch to ArchiCAD 10 will solve this and help us avoid delays due to updating.
I also saw something on this forum about large libraries...so I'll see if we can trim our libraries down.
Thanks again!