You didn't mention a router. With multiple PCs and if you want them all on the internet, you're going to need either a router or will be using ICS. I'd get a wireless router that has wired ports and go that route. You asked if your nVIDIA controller has wireless capabilities. Without more details, I'd say "No". So, to set up Ad Hoc, you'd need a wireless adapter in that one anyway. Get a router.
"host" "wired: SpeedStream 5200 Ethernet Network Modem" Desktop Windows XP Home Edition Version 2002 Service Pack 2. The network adapter is a nVIDIA nForce Network Controller, does this have wireless capabilities?
"client" HP Pavilion dv6315ca Laptop Windows Vista Home Premium Service Pack 1, 32 bit operating system. The network adapters are a Broadcom 802.11b/g WLAN and an Intel PRO/100 VE Network Connection.
Can I go wireless? I would appreciate a step by step guide. Thanks.