Yeah, my little SMC box combined with a linksys 802.11b (PCI?) card in my dad's pc the signal drops from very high when the two are 10 feet apart to very low when they are 25 feet apart and there are two walls between them. Again, I think it's just a low quality box because I've never heard anyone complaining about how their linksys card sucked, and the router has been cutting out on me recently.
I wouldn't recommend SMC.