[darkpuppet]

Your machine could, in theory receive twice as many packets from two lines, but in practice, it won't really happen. You could see a slight increase in web-page downloads if both lines are load-balanced, and maybe an increase in bittorrent, but you'd have to make sure the software is configured properly, and other services like gaming won't likely see any improvement.

The only real benefit is that you could have twice the bandwidth to share, so a few computers using the web at the sametime won't have much visible affect on overall speed.