Brand makes no difference unless they use compression protocols to speed the coms up. Most do (I know Belkin does). But honestly, most users won't even notice the difference.
Most cards and routers out there are both B and G. Any brand will mix and match just fine. There'* an industry standard. My laptop, Kim'* laptop, and my iPaq and Katie'* iPaq all came with wireless built in. All 4 of these devices work with all wireless routers I've encountered.