Having bought a motherboard with no wireless functionality I ended up having to get one of these. For the most part it's worked really well.

Transfer speeds are very much dependent on signal; Windows let's you know if the signal is poor - I found using a USB extension cable and placing it elsewhere improved things (being on the other side of the house to the router). We get a 15Mbit connection, which is about 1.5MB/s throughput, which I've been able to pull pretty easily.

The dongle has worked flawlessly on 32-bit Windows 7 for ages - however, I recently upgraded to 64-bit Windows 7 and for some reason I've been having to remove and reinsert the dongle after boot in order to make it work... I only have to do this once mind you.

Other than that it works fine. It's a plug and play - so no drivers are needed. The aerial also rotates from straight out to a 90 degree angle and comes with a stiff-plastic USB extension.