Tried your option A, no good, the max it allows me to put in is 7 MB.
Tried your option B, HQ video large gave me a finished job of 6.91 MB, tried HQ video Pal finished job of 9.17 MB. My original vid is 78.6 MB.
To go from 78 MB to 7 or 9 MB the vid quality is very noticeable.
Kev,I'm sorry but we may have issues, so at this point dont rush out and buy a GoPro.
To get on the same wavelength as you I fired up my xp machine and win movie maker and grabbed a 105 mb,mp4 file of my w7 pc which is an original file straight from the gopro
Issue I
It would seem that movie maker does NOT support MP4 file format which is the default GoPro file output.
I cant be sure if your service pack 3 version is any different, but a quick search at my end suggests it is a known issue.(to check yours for sure,in WMM,check the supported file types in the load movie menu.)
I then grabbed the same short clip which I had edited on WLMM and it was an AVI file of 73.4 meg.This was recognized by WMM on the xp machine, so I dragged it straight down to the timeline and hit save.
Issue 2
In the save options the best I could aciheve was
in best quality for my comp = 720 by 576 res at 15.7 mb
in best fit to file size it would not allow me to select higher than 15mb
in other settings/High Quality Video Pal = 720 by 576 res at 15.7 mb or High Quality Video Large = 640x480 res at 7.8 mb
In no way could I select a larger format (higher res ) to save at, and in fact when saved it came out at 14.7 mb.
So I'm sorry mate,I,m thinking we are at the limits of WMM.
My suggestions would be
a) live with the limitations of WMM
b) search for an editing program which will work on XP, support mp4, and allow you more flexibility in saving size options.
http://video-editing-software-review.toptenreviews.com/ Power director looks reasonable for the money.
c) consider upgrading to a 7 machine.( this by no means HAS to be a full blown desktop set up, there are many laptop options available which you could run in conjunction with your current set up.
Sorry I couldn't come up with a simple fix for you.