First of all, thanks for the help!
Here's the report from Speedtest.net:
[URL=http://www.speedtest.net]
[/URL]
I've done these tests before and found them to be somewhat all over the place. I'm unfortunately stuck with Time Warner Cable in Southern California, and they've "promised" that it's a 10MB/1MB package, but speeds change because of a variety of factors, most of them out of my control. Of course, if there IS something in my control, I'd love to know what it is.
As for the skirmish game, I ran this fine, but actually couldn't find where the Sim Speed Value was when hitting Tab? I never had any slowdown or frame rate issues, and I have a fairly decent system set-up. I've never had any offline performance hits, though I am playing at a high resolution so maybe I should bump that down when playing online?
System specs are:
3.15 Intel Core 2 Duo
XFX nForce 780i mb
4GB ram
GeForce GTX 260
HTO Striker 7.1 sound card
Windows Vista Home
blanking on the other important specs. 
I'm on a cable modem, and I haven't had anything downloading in the background or antivirus running, etc.
Thanks again for your help!