check this link every Sunday (they will post the links an hour before kickoff), they will post all the various ways to see the games. Some of the feeds will require you to have a certain program, read the FAQ, that will help. Each player plays a different stream, so it changes week from week as to what games are streamed on which program (hope that makes sense...basically TVUPlayer is my favorite, but the Bills games are not always available on there, when its not, I will use a different program).
TVUPlayer has been my favorite so far, as it seems to have the best quality with very little buffering. You will need to download the program (its safe) by searching it on google (its also very small). You also need to have the most current Windows Media Player.
I have also tried TVAnts and SopCast which for me dont seem to work very well (im at an Air Force Base for 6 months with my wifes POS laptop that we bought atleast 5 years ago, so I dont know if its the computer or the program, but the feed cuts in and out).
Another alternative is Justin.tv which you can access through things like XSSports, channelsurfing.net, StoogeTV. These sources can be hit or miss. XSSports seems to always have the game (to find the link go here, you will need to register and post two replys to any of the topics, then goto the week 4 topic where you will be able to see the hidden link in the first post) but can be a bit nerve wrecking as the signal can be a bit strained as the game goes on.
Good luck...keep looking you will find what you are looking for!