Hi Waka,
The previous posts have hit the nail on the head.
Firstly, reset your desktop resolution to the native resolution of your monitor. If it's a standard 19" (5:4 aspect), the native resolution is almost certainly 1280 x 1024. If it's a widescreen 19" (16 : 10), the native resolution will probably be 1440 x 900.
If your picture still appears too large, you will need to resize it. Do you have MS Office on your PC or access to someone's PC who has? If so, you can use Microsoft Office Picture Manager to resize it.
1. Take a copy of the picture file to work on.
2. Open MS Picture Manager (this can be found in : Start -> All Programs -> Microsoft Office -> Microsoft Office Tools -> Microsoft Office Picture Manager
3. Open the working copy of the picture.
4. On the menus, click on Picture -> Resize.
5. In the Resize window that pops up, select 'Custom width x height' and enter the appropiate values.
This will resize your picture (as opposed to cropping it).
Hope this helps.