Modem/Router has to connect to my desktop PC with an Ethernet cable?

[MurrayBrown]

When I was setting up our new and purportedly improved BlueSky WiFi (which it is not) I was advised by a Shaw Rep that one ethernet cable had to be plugged into my desktop PC.  There are only two ethernet ports on the new-fangled modem/router.  

Why?  Wouldn't my wireless desktop PC "pick up" the WiFi from the modem/router?

[mdk]

Yes, it should.

If you did not tell that Shaw Rep that your desktop has a built-in WiFi adapter, they were advising you that using a CAT-5E or a CAT-6 (but not a CAT-5) Ethernet cable is necessary, because a CAT-5 cable is limited to 100 Mbit/second, but the Shaw modem/router is capable of at least 1000 Mbit/second.