Ethernet AND a wireless card connected to same network?

[Scougar]

I recently upgrade an old machine (Dell C521) to Windows 7 Ultimate as I'm swapping it for a much smaller less powerful machine with my Dad. The network connection seems intermittent for some reason. At present I'm not sure if this is a chipset issue (Broadcom 440x) or my network connection etc. So, to get round this I've ordered a wireless card for it it.

So this brings me to the question. If I have the wireless card and the ethernet cable connected and the ethernet dropped out, would the PC swap to the wireless card for an internet connection etc? How does this work?

 

[KelDG]

When I connect my wireless laptop up to ethernet cable to transfer large files, it always seems to default to the wired connection. I would take a guess that it will default to the best connection, don't know for sure, but it has never given me any problems.