In reply to Enty:
> Can I reduce the size of it without losing quality?
In a word: unlikely. Quality and file size are trade-offs.
Want good quality? Then you'll need a big file.
Want a small file? then you'll get reduced quality (e.g. blockier/blurrier images, blurring on fast scene cuts, colour/intensity 'rainbowing')
Different compression methods might give you some scope for reducing file size, but not a vast difference. (cf. AAC vs MP3 vs WMA audio file size and quality; MP3 generally requires a bigger file for equivalent perceived audio quality)
> edited with moviemaker then saved
I'd be tempted to look closely at the settings of MovieMaker; I think it ought to have the ability to set the output compression format, the resolution (pixel dimensions, e.g. HD or standard PAL image size), and the image quality factor. I'd hope it would also be able to save a 'project' at highest available (from source media) format. But just because I think that it ought to, doesn't mean it does...