How many network cards in xp

XP will only use one network card for internet access

You can use at least distinct three adapters, but the configuration becomes problematic. Only one should have a default gateway assigned, and it is best to only use one NIC on any particular subnet. You can order their binding priority in Windows and may have to manually set up entries in the routing table.

Why do you need to use >2 physical NICs on a desktop OS?

While there are quad port adapters that will work with XP, whether that makes any sense depends on what you are trying to do.