If you get
$400 off the price of your computer, and then pay $790.20 at $21.95 per month (no
sales tax for services) over the next three years, you're getting those 36 months of service for the net cost of $390.20 -- which averages out to $10.84 per month, a nice price for an
ISP. This doesn't even take into account the additional
interest you can earn by keeping that $400 in your bank and spending it gradually as the ISP bills come in.
The major drawback then becomes the fact that you're locked in to MSN or Compuserve for the full three years, whether you like their service or not. That's more commitment than I wish to give to a modem-based ISP, especially with the ongoing trends in broadband access going on everywhere these days.