Your problem is not necessarily malicious software/malware or virus. It is fairly common to get a network install that will have a byte or two that is corrupted to a degree where the entire download is unuseable.
May I suggest redownloading the entire Service Pack IV to a backup a drive and installing from there. If it is ok, you should be safe in assuming that it is ok to burn. You may want to set the data verification option during the burn process. However, once in awhile a data verification won't suffice and you will still have a corrupted cd. If you are particularly paranoid, you may want to consider using a CDRW (read and writable cd) that can be rerecorded.
I had the same problem happen to me only a couple of nights ago and ended up having a corrupted CD even though I did a data verification. Also, make sure that you select the multi-session option on your burner so that you can use the remainder of the disk in the event you get a corrupted burn. You can then mark on the log of the jewel case that one of the sessions was corrupt. It would be helpful if you set the counter option -- assuming that your burner software supports this function. Generally Nero is supreme when it comes to burning software.