CPU: The Central Processing Unit, processor or just "chip" is the brain of the system. Speeds are measured in MegaHertz and faster is better.
DVD: The Digital Versatile Disk is an advance on the CD standard, allowing much higher storage capacities, enough to hold a feature film on one disk.
HDD: The hard disk drive is where the PC stores information long term, when it is not in use. Capacity is measured in gigabytes (GB).
MB: Megabyte, a measure of storage equal to 1,024,000 bytes. A single byte traditionally holds one character and a page of A4 text requires about 4,000 bytes (four kilobytes, or 4KB) of storage. A gigabyte (GB) is 1,024 MB.
Modem: Connects the PC to the phone system, 56K (kilobits per second) is now standard speed.
RAM: Random Access Memory, the storage space for the work the computer is doing at any given time. Measured in megabytes (MB).