I can see from other reviews that others are not getting this problem, but I've found that this device really, really struggles to maintain a good connection.
I'm using the thing in a school, and there's probably a fair amount of electrical "noise". The signal from the router is weak - my laptop with an internal card also reports this - but the laptop maintains a good connection pretty much without fail. This doesn't - at all.
It sometimes goes for periods without problems, and then drops / reconnects repeatedly, to the point that it's close to unusable. I've tried moving the computer around, and tweaking some settings, but to no avail. I'm using it with quite an old PC, XP SP3 and USB1.
This may be a one-off, and it's possible that it's a software / existing hardware issue, but if you think you may be using it in an environment where the signal is likely to be low and there's a bit of interference, be aware of my problems.