I need to purchase cards for my d300 which has just arrived. I want to buy from Cheap Chips and they have the following listed cards. What is the difference please?

CF Cards

Sandisk - Ultra or Extreme
Lexar - Platinum II or Professional

SD Cards

Sandisk - Ultra or Extreme III
Lexar - Platinum II or Professional

Also what does SDHC stand for and what does it mean? What does the Class rating mean ie; Class 6 or 10?

If it helps I want to get 8gb cards to start as this is my first DSLR. I will be photographing anything at the moment and moving into B&W Portraiture and some stock. Probably even some landscapes considering where I live.

All assisstance is greatly appreciated!