I've used the Farallon Skyline card in a Pismo laptop for over a year, and it works with my airport basestation. I don't know if the 1400 has a PCMCIA slot, but if it does, there are plenty of wireless cards out there that would work. Orinco and the Skyline card are the two I know work (Farallon has been bought out by Proxim, just fyi)
For the 7500, Proxim has a PCI card adapter for its skyline card, and that would seem a likely solution.
Check with Linkysys about the wireless/usb solution they have. Note, that Linksys deviced do NOT SUPPORT APPLETALK, which may cause you issues.