Are you compact flash card (i.e... for digital cameras) savvy?

I am going to purchase a new compact flash card for my Canon digital camera. I found one with 1 GB storage, and 120X (18 mbs). I found another with 2 GB, 80X (12 mbs). I am assuming mbs is the transfer rate - how many megabytes per second, how long it takes to upload the photos onto a computer. Is that correct? Does it have any effect on the quality of the picture? What about video quality? I'm drawn to the 2 GB because it will hold more and seems like a reasonable price (they are $26 and $40 respectively). And while I am here, what is the purpose of a flash card reader? How is it superior to using the camera and a cable? What does it do, and why should I buy one?
Please explain in detail, in layman's terms. Thanks for your help.

The card with the higher memory has the lower transfer rate... it's a trade-off. I'm wondering which is more desireable.

The transfer speed rate is to go from one picture to the next as you take them. Not to upload to the PC. As for the card reader, I have one because it saves the battery life on my camera. It saves me money in the end to not have to replace the batteries as often, specially when I have so many pictures to transfer. But if that is not an issue for you, then don't buy one. I also like the ability to simply take the card reader and card with me, without taking my camera when I am going to transfer pictures to or from another PC.

It is actually a matter of space. :) If you have the card it will not affect your pictures nor their quality. What it will allow you to do is to take more pictures at a time. The units come with some space and the flash cards will allow you to have more. That is about it.

Better to buy the faster card as it means that the camera will be ready to take the next pic quicker. Also, 2GB storage is obviously much better value and you will not regret it in the end.
A Flash card reader is not needed if you have the USB cable for your camera. Why waste money when your camera has one built-in?