Ultrapeers are used to create a better network. Right now you are running as a "leaf" which uses much less of your computer's resources. You are "shielded" from most of the network traffic, like searches.

When running as a leaf, you only have to connect to 3 or 5 (Pro) machines which run in Ultrapeers mode. You send your searches to those Ultrapeers, and they send it to the many more computers (~64) they are connected to.

The ultrapeers decide which search terms to send to your machine, based on your shared files. They only send the terms that may match your shares, which means your machine doesn't have to process all those other messages, which frees up your bandwidth from unnecessary traffic.

So, some machines act as ultrapeers if they are fast enough and can handle the traffic, which allows the leafs to run more efficiently.

Your machine looks to be *almost* capable of running as an Ultrapeer, but it wasn't working for you that well at first. So it looks like you are usually better running as a leaf.

Sometime when you don't have a lot of uploads and downloads happening, uncheck that "disable ultrapeer possibility" box and see what happens. It can be interesting, and if you don't share a lot of popular files, it's a very good way to contribute to the network by letting your machine do useful administration work.

Cheers.