Well...it's definitely NOT the scenario I had hoped for, but at least I've found a conclusion to this.
Thanks to Tiki and Jibi, as they've hit it head on. A missing .msi file is pretty much death for the PC. Luckily, all my specific stuff is network-based, so to re-image the HD is no big deal, as I can re-populate all my work stuff.
After my BB blue screened on me and lock up permanently, I called RIM BB support, and after 2.5 hours on the phone with them, we were able to get it back up and running.
I had to use a co-worker's computer, load DM onto it, and then downloaded the Cingular standard 8700 OS. It took some time, but we got the handheld wiped completely clean, and started from scratch.
Now that I'm at least functional again (albeit with the standard OS...yuck!), I'll wait until my IT guy wipes my computer, and then install the .284.
Thanks to everyone who offered their suggestions/comments. I'm just glad I'm back to normal.