LIPets

I have a win 2003 server, the raid array is c, e & F I installed on C and the drive filled up in short while, I deleted the log and the next day same thing. I tried to install on F but it went to the C drive again. Can I choose the location of the Log file or why can't it be installed on F? Last question why is it so big like 5G? What is the log file name? tks Bob