Now that I have purchased my first DSLR, the Canon D90, I am now wondering what SDHC card I should purchase. I want a very fast card that I can take multiple photos -- click, click, click -- without any stalling. At the least I realize I should purchase a class 6 card. However, card speeds can go as high as class 20. Sandisk makes an 8GB Extreme Card for about $50. Any recommendations on a SDHC card and place to purchase?