To quote John D. Ross from this SharePoint forum response at http://social.technet.microsoft.com/Forums/en-US/sharepoint2010setup/thread/2283d53c-50fd-4571-a6aa-f6eb6e91e2c5 "You can specify another drive -- but SharePoint will still put the information in the root folder (../14) on the C drive. It doesn't take up a ton of space. What takes up the most space on a SharePoint server are the index, log, and database files all which can easily be moved to another drive." I personally always install on the C:\ drive and have the log files stored on another drive because they can grow in size, but there are no hard fast rules. All the installations of SharePoint I have seen have also been on the C:\ drive. Hope this helps.