...for what to recommend when helping new members resize screenshots. For as long as I've been here (A little over 4 years now), they standard has been Irfanview.
Don't get me wrong, Irfanview is great, but I feel that there are better alternatives.
More specifically, Paint.net. I discovered it fairly recently, and it is a great free program for image editing/resizing.
My main reason for suggesting it is that it is VERY easy to get your images under 150KB. Unless Irfanview has changed recently (or I'm missing something), it does not tell you what size your saved image will be, making the process a 'guess and check'. Paint.net, however, tells you the size in the preview, ensuring the highest quality compression and the easiest way to save.
Paint.net can be found here:
http://www.getpaint.net/
If you would like, I would be glad to make a tutorial for resizing images in Paint.net.
/me