Hey smicale, I stream all the time and never have any issues, I've actually streamed a over 2000kbps to my job and it's been flawless. With you also having problems with local streaming it tells me something is wrong. It could be a number of things. Things to check out.... Use task manager when your streaming something to your local network and check the CPU under the processes tab, you can click the CPU column title and sort by highest CPU utilization. See if something is using up lots of your CPU while streaming and not streaming. This will let you know if it's raw processing power thats the issue.
The second thing you should try is a few video formats. It's possible that the transcoding (conversion of the video to a streamable type) is slow for certain formats due to the processing power on your machine.
If you fine in all cases that your CPU utilization is low then take a look again under task manager at your network utilization under Networking and see what the network utilization goes up to. This will indicate how fact your are able to send it out. If you are loosing speed due to your network you will see this here.
Let us know how you get on 