If you've almost used all your ram up then that could be an issue. I don't know how it'd affect your dwnld speed though. VM is also an issue. Virtual Memory uses your HDD space up. LW 4.2 is supposed to improve upon this with less ram & vm use. In my experience that's been true.

The reason I was asking about USB connection is b/c my isp strongly advised mac users not to use them. Some also power from the comp & some also utilise the comp's processor. Some macs have slow USB cards.