"wouldn't my BIOS system reject this card?" Not necessarily, no. The BIOS whitelisting problem isn't that is rejects all other cards, but that is rejects cards using a PCI ID that's not contained within the whitelist. According to the information at thinkwiki.org [0] there are some T42 models that came with an Atheros card (the ones referred to in that page as the IBM Wireless LAN Mini PCI Adapter things.) The bottom line is that, as long as it's a genuine Lenovo part, then the PCI ID will be already loaded in the BIOS and the BIOS will be happy.
That's what I did when I bought my X60s: I replaced the Intel WiFi card that came with it with another one (an official Lenovo part) that used an Atheros chipset instead. [0] http://www.thinkwiki.org/wiki/Category:T42
