Indeed Roger, I had forgotten that the US and European versions use different chipsets, I can confirm however that the Broadcom drivers don't work either (I tried it immediately after switching to XP64). Personally, I see little difference between wired and wireless internet connectivity - my connection speeds are if anything slower when using the ethernet port on the router - guess it's not gigabit (sigh).
I've spoken to (argued with) Linksys tech support this morning about their miserable lack of support for a) Vista and XP64 - Initially they wouldn't even admit there was a problem. They wouldn't give me any indication of a time-frame for a fix either.