I would imagine that some photo-editing software came with your camera. You can shoot your pics in the highest quality mode, then crop out all the unecessary parts of the photo. This will effectively increase the magnification of your picture when posting to the web. It will allow more detail to be seen. It will also show if you had the coin in focus or not, as well! You can also resize the photo, after cropping, to approximately 600x600 pixels, so you can post on the web.
If you don't have any photo-editing software, ask Bobby for the link to the free copy of Irfanware, which is pretty good for basic things such as cropping and resizing photos. If you are really interested in better photo-editing software to help maximize the pictures you take of family events, vacations, loved ones, etc., then you have many to choose from. I use PhotoShop Elements 6.0 which runs around $90, but can sometimes be found on sale for around $70. There are less expensive, and more expensive softwares out there...all depending on just what you want to do to your photos.
Can't wait to see some of your pictures!