You are now into the wonderful world of resolutions. Don't worry too much its quite normal for a scanned image to appear very large on screen. Its to do with the way that the screen shows images compaired to the way the scanner sees them. The scanner is able to see at higher quality than the screen (more dots in a set area) so when the screen tries to show the picture it has to make it larger.
You can either use the zoom out facility on may packages to let you see the whole image or you can resize the image to fit. The latter is better because the image you scanned in will have a very large file size.
If you use the software you have to reduce the size of the image say by 25% and save it as a jpeg (.jpg) this will make the image fit the screen and make it a better size to send as email and store.
when you scan an image, you likely scan it at 300 DPI or 600 DPI. When you view the file on your screen it appears larger because your screen will likely be nearer to 90 DPI thereby making the image "appear" much larger.
The easy way around this:
1) Check what resolution you are using to scan e.g.300 DPI
2) Scan the image at this resolution and remember it.
3) Open your picture using your Phote Editing software.
4) Most software editors have an option to change the resolution to a different size. I use PhotoImpact 7 and mine comes under the "Format" menu and is named "Resolution". Use this feature to change the image's resolution to whatever your scanner was set for. e.g. 300 DPI
Hey presto, your image is now the original size again and will print much better too.