I havnt got the camera to hand as its a friends camera (from uni)...And thats why its hard for me to get the footage directly onto the computer ill be editing it on....which is at college, if that makes sense?
Sure, that makes sense. Okay, so I was trying to figure out why you would need to go through Movie Maker. And that makes me think that you're probably using a camcorder that requires you capture the footage, from within the editing software. To capture footage, did you connect your camera to your computer via firewire cable?
If that's the case, then the problem could be caused at two potential places. You need to make sure that your capture settings are at the best quality.
After you've captured the footage, are you exporting it? Or are you just using the original file that was captured by your editing software? If you're exporting it, there could be an issue there.
I've never used Movie Maker, but the fact that it's free (and designed for the masses) makes me wary of it. Considering your issue, having to capture footage on one computer, then transfer it to another, I'd be inclined to recommend that you download a free trial of Sony Vegas. It's good for 30 days. Eventually you'll probably want to purchase it, but 30 days should be enough time to complete this one project, right?
EDIT: I saw your edit. Yeah, miniDV is captured via firewire.