Going to read the rest of your replies but I am sure some of this has already been said. From what I read so far, it is true that it depends on a couple things. How many megapixels the camera is capable and what settings you use. There are two basic settings. First is Quality which will be a few settings including Basic and Fine. Then there is the size which might be Small Medium or Large or it might be 800x600 1024x768... or even larger. Personally, with all the cameras I have ever bought, I have chosen to go with Fine and Largest file size to take full advantage of the capabilities of the camera. That will take the largest images.

Basically, you want to do that as you can always downsize a picture in software but you can't make them bigger. If you ever might want to print a large print you will be sorry if you didn't use the larger sizes. If you are only using the photos on eBay, then you don't need huge files but again, you can take a large file and reduce it to use on the net but you can't, then, take that image and blow it back up into an 8x10. So, always go with the largest images and highest qualtity that you can and when you edit your images do so from a copy of the file and NEVER save over your original. SAVE AS, as a new file name.

Basically, on the megapixel size, you will get fewer pictures depending on the size of the images that you are shooting. Larger pictures will yeild less capacity on the card.

In my opinoin, I would go out and get a new card for your camera. With memory as cheap as it is today, you can get upward of 512meg for less than 50 bucks. Even for my 10 megapixel camera that will give me at least 80 pictures. Plenty for a party or a small trip. I just bought a 2 gig card for the Nikon D200(10megapixel) that will get me over 200.

First a little primer. Megapixels is the result of taking the height of a picture and multiplying it by the width. So, for example, a 3000x2000 image is 6,000,000 or 6megapixels.

Larger size photos will take up more memory on your memory card or computer. I will put a small chart below of examples.

Looking back at some of my old pictures here is what I get. I have a 3, a 6 an 8 and now a 10 megapixel camera.

All these are based at the largest size image at the highest quality setting.

Megapixels - Image Size - File Size
Capacity (16meg card)

3mpxl - 2048x1536 - 1.1 megabyte
14-16

6mpxl - 3008x200 - 2.6 megabyte
about 6

8mpxl - 3264x2448 - 2.7 megabyte
About 6

10mpxl - 3872x2592 - 6.4 megabyte
2

Thus, like I said, get yourself a larger card. There is some thought that you might not want to have just one card. Because of chance that one might fail or go bad. Or you might loose it and thus, all of your pictures. Some people take their desired capacity and divide it among a couple cards to hedge against getting stuck without a card or loosing everything on a bad card. If you wanted a gig of capacity, you could get 1-1gig card or 2-512meg or 4-256meg. Personally, if you don't take tons of pictures or your camera isn't that high on Mpxls, I would definately opt with 512meg or 2 or 3 256meg cards.