reply to your post.
Before you attempt to format your system, I would recommend that you analyze and check the existing drives. It is possible that your Operating System is located in drive C of the hard drive (since it should be the default drive used when installing the OS), but you stated that you only have drive D and E. I would recommend these two options. I hope this could help.
To be able to determine what drive you are going to format, locate the Master and Slave drive of your system, since you have two hard disks. You can specify the Master and Slave by looking at the hard drive information written on top of it. After identifying which hard drive you need format, you can now select and start the process of reformatting the system. Insert the OS installation CD and follow the instructions.
Open the drives D and E and find the Windows folder, where most of the Operating System processes are located, and Program Files folder. After you have categorized which drive, you may start reformatting your system. Follow all the necessary instructions from the OS Installation CD. After installing the new OS into your system, it should be essential to install the required Audio and Video drivers, and other apps you require.