Most will work with windows 7, if the installation says it's not supported on this version of windows, all you have to do after plugging in the wireless adapter is go to your Device Manager, find the adapter, click Update Drive Software.
After that, it will have 2 options, choose the bottom one that says browse folders. Make sure your installation disk for your adapter is in your CD drive. Navigate to the CD folders, and select the DRIVER folder, click next, and you should be set, it will find it, and use it.
This is the one I use,
http://www.newegg.com/Product/Product.aspx?Item=N82E16833166022 . It worked with Windows 7 RC 32 Bit, but when I went to Regular Windows 7 64 Bit, it would tell me it's not supported when I tried the installation from the CD. I did exactly what I just said earlier and it worked.
If the installation works without giving you an OS unsupported message, you might want to still do what I said, It might be better to not install the device software and just the driver, because windows manages networks perfectly find, and it could cause problems/annoyances. Mine showed me connected to 2 different wireless networks at the same time when I was connected to one lol, so I went into MSCONFIG and disabled the program from starting up on start-up and let windows manage everything(this was on the 32 Bitt RC)
Edit: According to the reviews, there are now Windows 7 drivers on their website, so you might want to download those onto a cd or your Hard Drive and you should be set. The method I said works for other devices too in-case you ever need it anyway.