Did your cable modem come with a USB connection option or just cat5? Mine came with both and I found out that if I used the USB connection I had more consistent, and higher speeds on a regular basis. Just a thought.
Oh yes I just noticed something else that I know for a fact is giving you the request timed out error...when you go in the DOS you have to cd first thing to get to a plain on C prompt. It does this in XP when you have multiple accounts that you can log in to. Then after you get the plain C prompt type in tracert testmy.net>tracert.txt That should help ya some.