Chantal, do you have an LCD monitor? If so:
1) if your display looks either stretched or squashed, you could be running a widescreen setting on a conventional monitor, or vice versa.
2) if the display has the correct proportion but looks blurry, you could be running your picture at a non-optimal (aka non-native) resolution.
For both above suggestions, try selecting <Start | Settings | Control Panel | Display> and play around with the settings. Most monitors should be able to display 1024x768 pretty well.
If you still have no luck, you may not have the correct video driver installed, in which case you may have to track down your local nerd to help you out.
Good luck
