UPDATE [2.5.2011]!!!
Solution is now available for this right here!
Old post:
Recently tried to upgrade the 54mbit (abg) wifi card on my HP NX7400 laptop to the 802.11n standard. I'm sorry to inform you that this simply is NOT possible at the moment, unless someone manages to create a hacked bios. The problem is a whitelist in the bios containing which WIFI cards to accept. Only original cards are located in this, so no luck when trying to upgrade it.
What happens is you boot up and get a 104 error telling you to replace the mini pci wifi card.
If someone anyhow DO have a way to do this, PLEASE inform me/us here in the comments ;) The only way I know right now though is to use a USB or PCMCIA USB card.