Do you absolutely need an intermediate format*?
Doesn't your video editor support importing the image sequence? You could save time by skipping the step... You shouldn't need to move the images files on the disk if you're properly using recording tools like lawenarecordingtool and srcdemo2
Also, you shouldn't use lossy codecs (like h264/xvid) as an intermediate format because you'll end up with compression artifacts before the final encode. Look for encoders with "lossless" in the name.
If you absolutely have no space for lossless files...Look into 10bit encoders, totally might not be supported by VEGAS but you'll save tons of disk space.
*intermediate formats are not meant to be played, so VLC/MPC/WMP will have trouble decoding them smoothly.