SD cards are all basically the same as far as I know. I would go with cost vs. the hype used by some.
Ok as suggested in the other post , you need to move the files from the SD card to your computer to see what is there or missing.
You can go to a computer store and purchase an SD card and SD card reader for your computer if it does not have a slot for the SD card already built in. I have an old computer and using a reader plugged into the USB port and reading the card then copying the data to a folder on the computer allows me to save what ever is on the SD card.
Once on the computer, you can switch SD cards and copy the files to the new card.
Not all media types will work on all phones. Some will not be able to "read" the file type and it may show as corrupted.
Before you move any files to the new SD card you should format the card.
When you go to the computer store ( Best Buy or what ever is near you) they will show you what is needed to read your SD card and should show you how to move the files.
I would avoid being talked into bringing the computer into them to have them do the work. this can be expensive and you will still be left with no understanding on how to do this.
XP is not so old that it wont work. Your computer should have USB ports unless it was a stripped version.
Using a reader with the card in you should be able to see files. You may also need to download and install a driver to allow the SD card reader to work on the computer. when you buy on make sure it has the ability to work on XP or has software included you can copy to your computer.
This link may help explain how to see the info