Question : Problem: Using network cable and wireless together

What is the effect of running a wireless network adapter to the same router that the same machine is plugged directly into on a standard network card?

Can I get better speed/reliability? Will one just override the other?

Answer : Problem: Using network cable and wireless together

No performance increase but I have had issues running both. They tend to swap back and forth and sometime i have issues resolving web pages and network resources. For this reason I disable my wireless when I am hard wired. You may also want to take a look at this post:
http://www.experts-exchange.com/Networking/Misc/Q_22071833.html