EDIT: Sorry posted Out of Date info.
If you are using XP or 2000, then you can span and mount the 2 extra drives into a folder on your C drive.
The 3 drives need to be formatted as NTFS, then go to "Disk Managment", convert the 2 drives to Dynamic disks, then you can create a spanned drive across them, then you can mount it as a folder.
Alternatively (and more easily) you can mount Each extra drive as a folder.