Make sure you have enough memory to make buffer times short. If you can get rid of a few things that you don't need, that will make your memory larger. Start by looking through the task manager and deleting anything that you don't want. Getting rid of any spyware can also free up memory
Close any unnecessary windows while the video is playing. If you're watching a video on Windows Media Player or a similar player, close your browser. Try to have as few programs running as possible when loading a streaming video. This is an easy solution that will immediately improve the buffering time.