Ok, so I followed you guys' advice, or am in the process of it. I removed AVG completely as well as its toolbar. I installed, updated, and ran MSE. MSE didn't find anything. (Oh, and I was able to download MSE without issue before rebooting or doing anything but removing AVG.)
I rebooted into Safe Mode w/ Networking and I was able to start and complete a download. I'm not in the process of starting the service diagnostic. I'm still able to start a download AND buffer without anything but Microsoft processes running, looks like it's time to start the half-n-half.
I appreciate the help guys, it's killing me to figure out what's going on with this dang thing. I'll post what I find. Thanks again