I'm writing some data acquisition software and need a gui plotting library that is fast enough to do realtime updated graphs. I've been using Nplot which is pretty good for a free library, but I'm wondering if there are any better libraries (preferably free or cheap).
Definetly go for Zedgraph, we have been using this for years and it is very good in 'real-time' graphing. Zedgraph is very well documented and there are many examples available.