Why is my internet connection slow, modem problems?

I don't understand why interent is so slow. I have a Motorola SB5101 modem, and a Linksys WRT54GS wireless router. I also have a vonage connection. The connection is modem-vonage-router. I know the problem is not my laptop, because i can connect to a neighbor's net and it is much faster. The wireless connection list has my network listed, with access with full bars. So my question is what could be a reason for my internet being so slow? My network is password protected, and it works but very very slowly.