How to pick new hardware for database & web app server?

I work for a SMB. We’re prepping to refresh hardware for a particular database server that also hosts a web application (java, client / server). I wanted to ask for recommendations on what to focus on for this server. It is transaction based. Currently, it runs primarly on flat files but this may change to MySQL before the next refresh. It runs SLES.

I’m liking this model from hp. I went to hp first only because that’s typically who we buy servers from. Are there other vendors that have a advantage for this server type?

http://shopping1.hp.com/is-bin/INTERSHOP.enfinity/WFS/WW-USSMBPublicStore-Site/en_US/-/USD/ViewProductDetail-Start?ProductUUID=QOIQ7EN5I8wAAAEzlLNtcQa8