Many things come into play here. What speed is the router? From what you're describing, it seems like its a B?? also, what kind of wireless adapter is it? Wireless will always be slower than wired, but its not supposed to be that noticable. Some things to test: have you tested your laptop at other locations with wireless (is it slow there too?); have you connected other wireless devices to your router (same test, are those devices slower than before connecting to yours?) Basically you need to narrow down the problem and use multiple devices to test with to rule things out or in.
