Starting Fresh with 2011 new PCs installs. ( My PC Refresh Project )

So im currently looking to see what vendor or brand is the best for my Pc Refresh project. I however would like to get something that is going to stay working well for atleast 3 to 5 years. We currently have HP systems and I am a big Dell fan. Im currently eying the optiplex 780. Does anyone have any ideas or regrets on this product. I know my discussion is a bit general but I can add more details if needed. Thanks!