If you are still using windows-XP, and are going to use a SATA Hard Drive, then you are going to need a floppy drive for the SATA controller drivers that will be required to make the SATA Hard Drives work on Windows-XP. Although, there are programs that can rip a Windows-XP CD to include the drivers required to make it work for SATA controllers... but thats another topic to make if you get stuck!
You don't need a CD-ROM, DVD-ROM drives does a perfect job of reading CDs and DVDs as well.