Single disk for Data, System, User, Temp and Backup when installing Fail Over Cluster?
MSDTC has to be installed on a separate drive while rest can be installed on another drive.

EDIT

MSDTC is needed on separate drive because once you start installing SQL Server, the drive where MSDTC is installed won't be selectable and you will see message on screen something like "Cluster Disk 2 is already in use by MSDTC".  

Secondly, according to folloing article MSDTC is needed when you are using SSIS, which I am actually using.
http://technet.microsoft.com/en-en/library/ms189910.aspx