I use
Fenopy along with
Micro Torrent for hard to find software that I need for a short period of time, or would like a fully functional "trial".
Make sure your virus protection is up to date, keygens contain viruses sometimes.
As an aside, do you need Excel 2003 or do you just want to upgrade? Open Office makes a great (free) Microsoft Office alternative. Best of all, going from Excel 97 to Open Office's
Calc is easier than going from Excel 97 to Excel 2003!