Slow AirPort on MacBook

I'm using a dlink 614 wireless router.

All wired connections are fast.

My sisters wireless PC is reasonably fast.

My AirPort on my MacBook is slow.

I'm sitting right next to the access point with my MacBook, any ideas as to why it is so slow?

I tested the same download on my sisters computer and it was faster than 250KB/s. Her computer is also in the other room, which means her wireless connection travels a further distance and is also disadvataged with a solid brick wall.

So why is it that the MacBook is slower?

Some more information and bump in the thread:

When I am using AirPort wireless, the connection is unstable and generally a bit slower than normal. For example, if I try streaming a movie from YouTube the buffer will struggle to keep up with the clip.

I know it's something specific to this MacBook or the actual adaptor itself, or maybe its the compatibility between this unit and my access point. I know this because my sisters wireless USB adaptor works fine.

Also, when I plug in the ethernet cable to the MacBook the connection runs fast and fine...

When I get the chance, I'll bring the MacBook to school and see how the wireless connection runs there. I just can't do it at the moment because I don't have a carry bag for this laptop

i have a macbook pro and a netgear router its in the loft and i am in the living room down stairs

and im getting round the 360 mark
i have 4 meg broadband my router is the 108G wirless version.

i have a macbook pro but i have enabled "N" but i dont think that has anthing to do with it.

we have a d-link router at work and my macbook pro doesnt like connecting to it. but i think thats jus the router the connection keeps dropping off on both wired and wirless connections. i dont just dont d-link routers anyways.

i would suggest trying 2 different router from Netgear or even an apple onf if your budget can reach that far.