I decided to buy one of these today as my other wifi card was causing many problems.

Did a bit of research first to find out its compatability with Windows 7.
Turns out its not as easy as plug in and go.
Theres a nice guide on this page:

http://www.phishthis.com/2009/01/16/how-to-install-wmp54g-drivers-on-windows-7-beta-64-bit-or-vista-64-bit/

If you look at the comments, theres one guy who stated that a different driver worked with his revision 4.1, which is what mine (and probably all new ones) is.

Worked like a charm and now I get 4/5 strength instead of 2/5 compared to my old card!