Just bought today and also had the excruciatingly slow download speed for the initial installer file. Thanks Ripper for posting the VPN fix/workaround! I downloaded one of the free VPN apps and my PC downloaded the file in seconds. I turned off the VPN after I downloaded the installer and my PC downloaded the game (500+MBs I think) in a minute or two. Anyway, thanks again for the tip! I'd +1 your rep if I could, but since I can't, here's +100 to you sir.
p.s. I know Comcast was mentioned somewhere above as a possible culprit, and yes my ISP is Comcast.