sopcast.com , download it and there are always about 3 channels for each race, decent quality and best of all FREE.
I've used it many times for watching soccer,football, and F1 and have never had trouble. Very easy to use, decent quality, and plenty of options for F1 so I usually listen to the English commentators. The English ones are live, so you can use the live-timing off the F1 website.
Thanks man,but before i download it i have a question,you see my computers memory is 128 Mb RAM and 4 GHZ,so will it lag or something for me? and what channels show F1 live?