Building a wireless router

Would one wireless card in it be enough?

If I wanted, could I use two without any interference?

Okay, back from vacation.

I've scooped out a cheap wireless card I can use.  I have a question, how many bytes per second can a 333 MHz processor handle?  I read (in the Linux kernel documentation, IIRC) that 10 Mbit/s is enough to swamp a 100 MHz processor.

I will be using FreeBSD.

If I somehow set things up to pass data directly between the NICs, how much data can PCI handle?  133 MB/s according to Wikipedia.  That'll do, as I have no better options, and my cards use 802.11g which runs at a theoretical maximum of 54 MBit/s.  My Internet connection runs at around 10 MBit/s as well, and I don't transfer large files over my LAN very often.