On the subject of the network card:
If the linux distro will be running in virtualization or emulation software like QEMU or something, you need the PC-BSD machine with a working network card + a linux distro that supports the networking card emulated by the program it runs in (e.g. qemu) not the local card.
If you are installing GNU/Linux into a different partition rather then a program, you'll of course need one supported both by Linux and BSD.
As far as networking cards for Free/PC- BSD and OpenBSD...
It all depends on chipset and interface!!!
If THIS is the card you mean by 'Linksys Wireless-G PCI Adapter card', the card is supported. If not, well -> more info required.
Some time ago, I did a search of cards available in my area and made notes on the ones compatible with *BSD.