The official release of Ubuntu 9.04 - Jaunty Jackalope is fast approaching. When it's released on April 23 you can be sure that Canonical's servers will be getting slammed. That means the downloads are going to be slow. The good news is that they just let loose the Release Candidate for Ubuntu 9.04. There should be relatively few changes between this version and the one that will be released on the 23rd. If you update your system to this version now, you'll only have a few updates to apply on the 23rd.
To update from version 8.10, see the instructions here. If you prefer to download an iso file, downloads and torrents can be found here. The torrents are running pretty fast right now. The i386 torrent only took a couple of hours last night.