Depends on the OS. (operating system) if you have any type of windows, youre screwed. You'll have to reinstall the OS and you'll loose everything on the computer.
If you have Linux, just run the config tool for the HD. it will be hda, or hdb, and you can change them there and just reboot and win.
The system partition(a partition where the operating system is installed) is the active partition of the Hard Drive
system partition
System partition
Most of the time the boot partition and the system partition are the same partition on the drive C.
The area on the hard drive that contains a map to all the partition on the drive is called the partition table. That is what partition utilities edit when you add, delete, convert, or resize a partition.
extended partition
Most of the time the boot partition and the system partition are the same partition on the drive C.
By default C: is the active partition of the hard disk drive
active partition
You just partition the Hard drive not the RAM.
To remove a partition on a slave hard drive you can go into the BIOS. You should look up a guide if you plan to do this.
in Linux this is the second logical drive inthe extended partition on the primary slave hard drive