Best wifi USB adapter for a budget gaming build

[DirtDiver7]

Hi I'm looking for the best wifi usb adapter for a budget gaming build that I'm working on. I'm looking for something in the price range of 1-20 dollars preferably from amazon. I want to get a usb adapter rather than a pci adapter because I want to have the option to add another ati 6870 in crossfire later on (also the reason for the over kill psu) and it looks like my motherboard only has two pci slots.

here are my components.

CPU $120: i3-2100
Intel Core i3-2100 Processor 3.1GHz ...

Mother Board $75: Gigabyte Intel B75
Gigabyte Intel B75 LGA1155 AMD Cross...

GPU $170: SAPPHIRE Radeon HD 6870 1GB
http://www.newegg.com/Product/Product.aspx?Item=N82E16814102948

RAM $24: Kingston 4gb
Kingston Technology HyperX Blu 4GB 1...

PSU $80: corsair builder series(700w)
http://www.amazon.com/dp/B001IZ7MHU?tag=banforbucga08-20&camp=213761&creative=393545&linkCode=bpl&creativeASIN=B001IZ7MHU&adid=1PC0E3KWDRTKKNEC9X4G&&ref-refURL=http%3A%2F%2Fgamingrig.blogspot.com%2F2012%2F06%2F1500-gaming-pc-june-2012.html

HDD $70: Western Digital 500GB
Western Digital Caviar Blue 500 GB S...

Case $60: Cool Master HAF 912
http://www.amazon.com/Cooler-Master-Tower-Case-RC-912-KKN1/dp/B003ZM7YTA

Optical drive $17: asus
Asus 24xDVD-RW Serial ATA Internal O...

OS $100: windows 7
Windows 7 Home Premium SP1 64bit

Monitor $120: 1080P 23”
http://www.amazon.com/AOC-E2351F-LED-Monitor-Black/dp/B0071CVTO6/ref=sr_1_10?s=electronics&ie=UTF8&qid=1340119481&sr=1-10&keywords=monitor+1080+x+1920+23

Thanks for any help you can give me. This is my first build so I am not very good at stuff like this.

 

[mcnumpty23]

depends what you mean by best

if you need a strong signal reception then would recomend something on these pages

i use one to get through my thick victorian brick walls as most usb adaptors i tried didnt cut it

bit over $20 though

http://www.amazon.com/s/ref=nb_sb_ss_c_2_8?url=search-alias%3Dcomputers&field-keywords=alfa+usb&sprefix=alfa+usb%2Caps%2C439

 

[DirtDiver7]

Best answer selected by Dirtdiver7.