It really depends on the software you are using. Are they straight streaming? Are they using Windows Media Encoder or Flash? Are you trying to do multipe sites at once?
128 up is not that fast, but if you are using some sort of Flash based variety web software, wlthough there may be some lag, as long as your PC can handle the cache it should be fine.
If you want it to be as close as possible (especially if she is using sound with a mic or something), you may want to look into some upgrades from your provider.
I wish you luck. I have had to deal with shit like this in the past so if you have any questions - just ask
DR