I installed my copy from a downloaded version mounted with alcohol because I can download 750k a second as opposed to stardocks really crappy 25-50k a second... (which seriously, if you're going to run a download games online business you need to speed that up.. it's a big reason why I never buy games on there...
As a loyal customer of Stardock for many years, and as one who has purchased a lot of its games, I feel that I must intervene :
I have a very reliable and stable high-speed cable connection (Videotron : Montreal, Canada).
I honestly certify that
my download speed from Stardock's SDC service has always been 750 to 825 kb/sec. (during the past two years).
(I cannot certify what it was like before 2006 : I do not remember.)
I am sorry to say that if you experience a mere 25 to 50 kb/sec. when downloading from SDC, and then possible lag when you are trying to play
Sins with your friend, one could suspect that something is wrong at your end.
I do not want to be nasty. I am simply speculating.