Win 2K Server Pro and SQL

I have the Professional Edition of Win 2K server which did not include SQL. I downloaded the evaluation copy of SQL from Microsoft and tried to extract it to the hard drive. When I do I get an error that says “not enough disk space on drive c:\ to extract. Please free up 515.x MB and try again.” When I check the properties of c:\ there are 19 Gigs free on a 20 Gig drive. I am going to try to download another copy and see if it is just the extraction file that’s messed up (about 2 hours over a T1 connection) but has anyone had this type of disk space problem before or know how to fix it?