these are pretty much guaranteed to work right? Also what do you mean by refurbished, it can mean different things...thanks!

Yes they work great - no complaints thus far. Refurbished means the product was returned for one reason or another, they were tested by NetGear, and released as good. The term "refurbished" can mean a lot of things to different companies. Companies like Lexmark or D-Link tend not to have a rigorous process and it may actually not be tested. But I think you're safe with companies like HP, Sony, Netgear, etc as long as you see an official seal of approval.