[kismac] Recommendations for high power "g" cards to boost speed?

I know this may be bordering on being off topic, there being only a small mention of KisMac, but I am hoping someone can give me some hardware advice for my wireless network.
I just upgraded my home network from 802.11b to 802.11g with a Buffalo WHR-HP-54 router and WLI-CB-G54HP PCMCIA card for my powerbook, both advertised to be "high power". I am noticing that my data transfer rates for copying files between my computers slow down by half when I move the powerbook from the room with the router to another room. When near the router, I can copy a 103mb file from a wired desktop to a wireless powerbook in 1:05. In another room the time increases to 2:09. And if I try a regular Buffalo WLI-CB-G54A card, it is even worse, slowing down to 802.11b performance, so I know "high power" is essential to keep the speed up. And my home is not a large, being about 1300 sf.
I am wondering what high power cards or routers members of this group could recommend to maintain full "g" speed throughout my home and what others are seeing for their "g" network speeds on Macs. The card for my powerbook needs to be PCMCIA (or possibly USB 2.0 might work since I have a USB 2 adapter for that machine). I would prefer the card to work with the Apple Airport driver or an open source driver, but would not rule out using a third party closed driver.
And it would be nice if the card works with kismac for identifying available networks and signal strength while traveling (especially if the card is not driven by Airport software). 

Also, has anyone tried the Hawking router and card for speed?
Also, I am curious what high power cards work with the MacBook Pro's Express Card slot, as it appears that Apple laptops have abandoned the PCMCIA slot. 

Thanks in advance.

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