OK, so after talking with Comcast and Terraserver, the issue is...neither of them! If I take my computer and plug it directly into the modem, Terraserver works just fine. But if I try and get the site running while using my wireless connection, it doesn't. So, nobody was blocking anything, the problem lies with the wireless router.
The question now is, does anyone have the slightest idea how I'm supposed to fix this now? I've logged into the wireless router's control panel whatever thing (at this point you should be able to easily discern my level of computer knowledgeableness), and can't find anything related to what I need to fix. The problem is that Terraserver is pulling map data from tsms.terraserver.com, and that is the linkup that I can't make for whatever reason when using wireless.
This is all slightly weird as it happened all of a sudden, but whatever, the site does work when I plug right into the modem so we've basically eliminated my ISP and Terraserver from the equation.
So, what am I supposed to do now to get this cooperating with my wireless router again? Ideas?