The ability to shot photos in low lighting conditions have nothing to do with the mega pixels on the sensor, it has to do with the quality of the CCD or CMOS sensor. The "grainy-ness" in digital images is know as "noise". Some cameras are noiser than others when you boost the ISO setting. Here's two excellent Internet resources for researching how digital cameras, of all sizes and prices, function in the field:
www.dpreview.com
www.imaging-resource.com
When it comes to low-light photos at WDW (parade, castle, fireworks, Osborne lights, etc.) the best thing to do is to try and "anchor" the camera as best as you can. No matter how hard you try, you can't hand-hold a camera still enough to make most images worth a hill of beans. The three best things to use at WDW for steadying a camera are: trash cans, fence railings, and lamp posts. A fourth good one, when the crowds are light enough, is Main Street itself.
Trash Cans: The cans at WDW have FLAT tops and are numerous. Rest the camera on top. If you need to tilt the camera upwards, place a folded napkin under the front of the bottom of the camera to raise the lens up. I got lots of good ambient light (camera-speak for "no flash") photos from the Osborne light this year using trash can tops.
Fences and balconies: Same deal. I got some great shots of Illumunations by using the fence railing around the lake in Epcot and the railing of our balcony at the YC.
Lamp Posts: Excellent for vertical photos... especially castle photos.
Main Street: This one's a little tricky and only works when the crowds are very light. One of the tricks to interesting photos is to use something OTHER than eye level to take your pictures. Get "high" or "low". One time I got some good photos of the Main Street stores with the castle in the background by laying down on my stomach and placing the camera directly on the pavement. I know it looks funny, but it works.
Also, sometimes blurry photos can be very cool! I took a good photo right before FITS of the vendor next to us that was selling the light-up/spinning toys. Again, I used ambient light and got a long exposure that showed the light trails the toys made as they spun on her cart.
Cards... As noted, the prices of memory cards just keeps falling. I bought my first CompactFlash card in April of 2001. It was a 64 meg card and was on sale for a good price of $99. This month I bought a Sandisk 256 meg CF card for $59 ($49 after rebate). You're in the catbird seat if your camera uses CF as they've always been cheaper than the other formats. Right now Dell and
Amazon have some of the cheapest prices around. Dittos for Sam's Club. Ironically, camera stores, discount mass merchandisers like Target and Wal-Mart, and electronics stores like
Best Buy are some of the pricier places to buy digital media.