Considering we are playing Manchester United there will be a lot of streams available tonight.
Streams will appear here from 7pm.
If you are happy watching a flash stream then that is fine. However, if you want to watch a HD quality stream that won't lag then I would advise downloading this as it is needed for running their best quality streams. You can find some help to how it works here. I use this all the time an it is just as good as watching it live on Sky.
I'd also check @bloodzeed on twitter. He always has excellent streams through the same service or SopCast. He is probably likely to stream the Arsenal v Liverpool game but it will be worth a check around 7.
Hope this helps.