wifi between two pcs

Open Windows Help and Support, type Ad Hoc to search field and press Enter. You get a list of support articles about Ad Hoc networking. Click the title Set up a computer-to-computer (ad hoc) network and follow the instructions.

Kari

Windows 7 Help and Support said:

What is a computer-to-computer (ad hoc) network?

In an ad hoc network, computers and devices are connected directly to each other, rather than to a hub or router. People generally set up these networks to temporarily share files, presentations, or an Internet connection among multiple computers and devices. Computers and devices in ad hoc networks must be within 30 feet of each other. Ad hoc networks can only be wireless, so you must have a wireless network adapter installed in your computer to set up or join an ad hoc network. For more information, see Set up a computer-to-computer (ad hoc) network.

Why did you feel the need to put in a another wireless adapter?

Ok i misread your first post, you want a wireless card for your desktop. you could get one but i would get a wireless router instead.

I find it easier to:

Modem
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router ---wireless---->laptop
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ethernet (LAN)
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desktop