cable...

If you have cable, you are at the mercy of "how many people are on the cable network" since it is a shared connection. this is the major cause of most slowdowns.

usb modem connection

slowness can also be caused by using a USB connection for your internet! use ethernet instead. this is the 2nd major cause of slowdowns.

routers

routers slow down and lock up and act flaky and drop connections if they are not running dd-wrt firmware. you may need to power-cycle them periodically, especially if you are on wireless. this is the 3rd major cause of slowdowns.

sattelite

If you have sattelite, it's going to be slow due to large signal latency (signal delay between earth and sattelite and network retransmission delays BOTH directions). typically a TCP protocol transmission sends a request packet (send delay), and then waits for an ACKnowledgement (receive delay). so with TCP protocols you are doubling the latency of whatever transmission line you are using. this is the 4th major cause of slowdowns.

768k internet

having low bandwidth internet will slow you down to some degree. this is the bottom-of-the-barrel broadband.

will wireless cause it?

not likely.