Wireless problems with 9400/e1705 - 54mbps - 5.5mbps

Can someone please help me out here. Got a 9400 with the Dell Wireless 1390 WLAN minicard. Have never had a problem with the wireless until now. Our new router is a Linksys WAG354G. I can connect fine but its extremely slow and the signal is very noisy according to the dell wireless wlan utility. Signal fluctuates from 54mbps to 5.5mbps. Very rarely do i see 54. Usually at 36 or 18mbps. Funny thing is that the router is 30cm or less from the laptop. If im the only one on the network, it plays up. If the other 3 laptops are on the network, it also plays up. However, the other laptops do not experience this problem - only me. So, im not too sure if: - My wireless card is faulty. Used to work perfectly but now doesn't. - Router is faulty. But still works with every other wireless pc, so obviously not. - Dell wireless card has a problem with this linksys router??? Thanks in advance. Cheers; Matt.