There's a lot of versions floating around the internet. Don't download the one from steam, that will lead to sadness and a failed Source alpha. Easiest way to know it's the right one is download it from here: http://robzienert.com/dpb/dpb21.exe
__________________
a.k.a Adrenaline; Digital Paintball dev
Why pay for one when it's free to host? I have a server currently running titled A-Rabs United. I plan on keeping it live for a while. My steam name is shutout and ingame name is [ARU]carbonFybr.