Why is my laptop favoring the wireless connection over my LAN connection?

Try: Network and Sharing Center > Change Adapter Settings > Press and release Alt key to show the menu > Advanced > Advanced Settings

Move the LAN adaptor to the topmost position (This window says "Connections are accessed by network services in the order they are listed")

See my answer to this question.

You can set your laptop to "prefer" the ethernet conenction over the wireless. Technet has a quick overview:

The short answer is that Windows (Vista, 7, 2008, and I’m pretty sure XP and 2003 does as well) [or should do] this by default. The key here is the network interface metric. When you have more than one default gateway defined [...] then the internet bound packets go out the interface with the lowest metric.

[...] You can, of course, permanently alter your metrics by editing your TCP/IP settings on your network adapter’s advanced settings.

[...] You should know that Vista made a change to how we handle existing sockets – after plugging in, connections will not be switched over, you must re-establish the connection in order to make use of a wired connection. For example, if you’re downloading something from a website and realize that it would go faster by plugging in, you’d have to cancel and start over after plugging in. This is a change from XP and 2003.

For how to change these setting, have a look at this Microsoft KB article.

Go into your device settings. Look for your wireless card and go into properties, look fro advanced settings for the wireless card. Look for "Disable upon wired connect". Set this to enable. What this does is that if the system sees a wired connection with link, then the wireless card will automatically disable itself.