I have a new plesk 5 box. In the last 5 days my bandwidth has jumped 10x it normal daily usage. One day was 100x more than usual. I don't have a lot of sites on it and plesk reports very little usage of bandwidth. Does anyone know a way I can check to see where this bandwidth is going to or coming from.

First, you could check each site's bandwith usage if you don't have too many of them. Second, you could check Apache access logs.