Looking for Answers about SanDisk Ultra 4GB Secure Digital High Capacity (SDHC) Memory Card?

considering an 8MP images, this card can hold about 1,500 images

The SanDisk Ultra SDHC 4GB card is one of the recommended cards for this camera. The card can hold approximately up to 81 .tiff only pictures or approximately up to 817 .jpeg only pictures.

No, you will need a card reader that specifically supports SDHC cards.

Yes, this card is compatible with your camera.

You can also refer to the link below to know the compatible memory cards with your camera:
http://pct1.sandisk.com/ProductList...

Yes, you will be able to transfer the data from the your Windows XP computer to the card.

The Class specification only refers to the minimum transfer speed. Class rating also only refers to a specific type of transfer using small transfer sizes. Class rating only comes into play when considering HD video capture. Since HD video capture uses a smaller transfer size but the speed must be consistent throughout the entire video capture a sustained minimum speed is required.

The 15MB/s transfer rating of the card is the maximum transfer speed. This generally comes into play for shooting still images where the transfer size is larger. Writing the larger data transfers to the card quickly helps boost performance in burst shooting mode for example. Additionally these are the transfer speeds you will generally see when using a high speed card reader to transfer the data to the computer.

Not knowing the type of camera you have or what settings you'll use on it, makes it hard to answer this question. I've uploaded a general guide on the amount of pictures you can expect out of different sized cards and different Mega Pixels used. If you look around on best Buys web site I believe they have a similar giude if not the same one. You can also do a search on ask.com or google.com and they can provide you with a guide as well.
Hope it helps