Lets talk uplink speed
 

Currently I am on a 10mb and I get around 140,000 to 180,000 pageviews a day and around 4,000 post. Around 550 users online at once. I understand that upgrading to a 100mb connection will "help" things but what is the true effect it has on vbulletin? Is this a bottleneck area for mid size boards like mine.

Maybe a faster connection isn't what you need. Have you tried the optimization tips in my guide? If you follow as many of them as you can, it should help you immensely, not only with cpu/server load but bandwidth as well.