Do these wall-plugged extenders work for wireless networks?

[GhostGT]

And when I say work, I mean get the signal boosted up considerably?

I have two laptops and an Xbox 360 downstairs that don't usually get full bars off my wireless network.

To keep this simple....can I just buy these, set them up, and expect a good boost in performance? I've heard conflicting reviews about such things. Also, any alternatives? I can't go wired sadly..


Cheers,

Chris