I assume you want this to be a standard? as you have mentioned the 802.xx standards. Of the shelf wi-fi cards are nice and cheap, but can be horrendous to interface with (PCI, compact flash, PCIMA), and if these are to be used for small microcontroller apps, where portability is a concern, they eat power too.
This guy has documented a ncie little project, but the wifi card can be tough to get hold of (read: old).
http://www.harbaum.org/till/spi2cf/
As far as using a standard protocol is concerned, you're looking at either having to hack an existing device, or interface with it. Bluetooth dongles are cheap, and with the higher datarate of blueteeoth v2 might be an option. For that you would need a USB host, which I believe FTDI do rather cheaply, but may require a lot of software.
FTDI Products
There are some OEM bluetooth modules that communicate using SPI/UART available cheaply, designed purely for embedded apps, negating any nasty over-complicated interfaces:
SparkFun Electronics - Bluetooth DIP Module - SparkFun
SparkFun Electronics - Wireless
Bluetooth has the advantage of making the PC software end a bit easier.
For PCI, a CPLD/FPGA would be mandatory, which would just increase the chip count/hassle a lot more. Not to mention finding decent PCI specs without paying through the nose is tricky. But theres a way around this too. Yep you've guessed it, OEM 802.11* modules.
NXP Launches 802.11n Module to Boost Wireless Home Connectivity
Digi-Key Part Search
Relatively new, its tough to find a good distributor, and to find a cheap one. It should satisfy your need for high throughput and connectivity.
If you're jsut after a one-off, then perhaps nordic devices would help? Datarate wise, they are on parr with zigbee, but many support burst mode (which you could abuse for just brute force datatransfer, ignoring any 'network' features) up to 1MB/s datarate. You'll need a micro at each end, and to connect to the PC, probably some form of USB bridge...its all starting to add up.
If you've got the time for a complete custom setup (non commercial) then you could always use some A/V modules, with 6MHz bandwidth and analogue signals you can get some impressive datarates out of them. I've managed 20MB/s using CPLD's, point-to-point with a very basic protocol. But alas I think its somewhat illegal.
Sorry if I'm ranting, but I'm not entirely sure what direction you are planning to go down.
Blueteeth