[Skie]

0_o Methinks everyone's been on the sherry.

A device with multiple network interfaces can connect to multiple networks simultaneously. Each interface gets it's own IP but with consumer versions of windows controlling what goes on isn't simple to make work properly and it will usually just pipe everything down one connection unless you want to get balls deep into the wonderful world of bridging, interface priority and human sacrifice. Speed isn't really the thing that decides which interface is used, it's much more arcane than that.

Should you do it? Not if you're just doing it to the same network, and doing it on different networks requires a fairly special use case for people at home. Theres no benefit at all to doing this on the same network, you'll just get lots of weird issues that are a complete pain in the arse to trace and figure out whats going on, but by default Windows will just choose a connection to use and stick with that until you disable that interface (if it drops there is no guarantee it will failover to the other one, because it's stupid).