Thanks so much for the help, guys. Here's some more diagnostics:

- I tried switching the 200' run to a different port on switch #1, and nothing has changed

- the cable ends LOOK good to me, but what do I know?

- I've gotten some rough speed test results from that test that Speakeasy has, and here's my results:
-- when plugged into switch #1, I get 30/5Mbps, which jives with what we should be getting from Cox, our ISP
-- when plugged directly into the end of the 200' run, I get around 18/5, which I figured was reasonable given the distance, is that correct? Or should it still be 30/5 at that point?
-- when the switch is added and only my computer plugged in, I get varying results between 300KBps and 1.6Mbps down, but the whole while I still get 5Mbps up.

Any more ideas?

*edit*
Oh, and putting in a brand new switch in place of switch #2 does nothing at all.