as far as pci interface cards go just google for whats out there mac-wise. 

as for a router..  linksys is by far the best in my opinion.  for the same price as the airport base station you could get a linksys router with easily 4-5x the features and capability.  great embedded linux implementation also.

Edited by (05/27/07 02:46 PM)
Mac mini C2D 1.83GHz - 2GB RAM - 200GB 7200rpm HD
Sawtooth w/G4 1GHz - 1GB RAM - SIIG SATA w/2x1TB HD
B&W w/G4 600MHz - 1GB RAM - 2x80GB HD
Sawtooth G4 400MHz - 512MB RAM - 40GB HD
Dell Ultrasharp 2007WFP 20" Widescreen LCD
2.94TB Total Storage