My wireless connection has suddenly dropped within the last few days to less than 15 Mbps.

I'm connected and can use the internet but sometimes it's ungodly slow.

I have an Inspiron 1501.

I accidently disabled the radio the other day (FN-F2) combo but re-enabled the Radio then used that to turn it
on. However when I hover the mouse over the connection it's usually ~11 Mbps and Signal Strength is always
very low. By hitting FN-F2 to disable then enable the Radio, Mbps jumps to 54 Mbps for a short period then drops.

I've rebooted the router and set the channel from 3 to 6 to 11. But so far nothing.

My pc hasn't moved, no new equipment.

How do I tell if my wi-fi card is bad or it's my provider ?

Thanks, Gadrin