ok heres what happened to me... not much really but,
tv tuner stopped working, tried setting it up again and all that... didnt work.
dvd drive stuffed up. usually when installing games it spins really fast and loud.
but it would only spin very slowly and quietly.
therefore installation for cod4 took about 45 minutes.
both problems were fixed when i uninstalled SP1
cod4 installed in about 5 minutes