Can you take the wifi card out of a laptop

Probably not, since most laptops don't use a wireless card like you're thinking, more a wireless chip that's soldered directly onto the motherboard.

I noticed that you had another post about using laptop parts in a desktop, and probably the only part you'll be able to use is the hard drive.
 
Most laptops use a 2.5" form factor for their hard drives which is identical to the standard 3.5" drives, except they're smaller. So yes, you can use a laptop hard drive in a desktop computer. I am right now as a matter of fact.
 
Since the hard drive already has Windows Vista installed on it, if I plug it in to my desktop, then will it load Vista right off the bat? I plan on saving as much money as I can including saving $100 for an operating system.
 
I wouldn't recommend it. The copy of Vista that is already on the hard drive has registries that will only work with the motherboard and specific parts of the laptop. I would recommend a fresh install of Windows.

Having said that, there is no harm in trying, and it is possible that it might work. But the chance is very slim, and you may just have to bite the bullet and reinstall Windows.
 
A reinstall of Windows won't simply fix everything to work with the new hardware, it will require you to wipe the hard drive clean. To save any data, you will need to make a back-up/clone of the existing drive.