FYI: The MK II uses both Compact Flash and Secure Digital cards (dual slots). There is a good bit of debate ongoing about which to use and why, but, the majority of folks use CF cards, which are getting cheaper all the time.
Also, you need to realize that you have purchased a Professional photographers tool, which requires work well beyond shooting images. You are now the photographer, photo lab technician, editor, etc. WORK FLOW is a term that you will become familiar with real soon. While the MkII and other 1D series cameras (before and after) will provide good results, they will pale in comparison to one of Canon (or Nikon's-Armin) consumer digital SLRs. The cameras are desgined to do things differently and both have their limitations and strengths. The pro cameras are made to shoot fast and withstand the rigors of field use, while the consumer line is suited toward providing a more-immediately usable image; IE: better eye-appeal in more saturated colors and sharpness. The pro camera has more adjustability, well beyond the usual controls, but rather in tone curves, parameters, etc. Lots to learn. The MK II requires either a firewire or USB 2 interface in order for the camera to communicate with the computer to make many of these adjustments. (The 1D uses firewire.)
This may all be common-knowledge to some of you, but for others it's not. I mention it to aleviate any discussions about what camera is better, when the real answer is all of them are great at making images in the areas they are designed to excell in. The color from a 20D or N70 will smoke a MK II, straight from the camera; however, with some set-up, both will blow your mind. On the other hand, once you've shot with a pro camera, it's hard to go back. The focus is lightning quick and the shutter release is noticably faster. Bottom-line, as someone has already mentioned, it's the camera operator that makes the images.
Wannabe: Being a drag racer, you may be able to appreciate a look here: