Slow down there.
You don't have to reinstall.
You MAY have to get dirty on the commandline though..
You say you dug up the key, and I am guessing you know the SSID. If not, you should be able to find these by booting back into Windows and writing down the info.
You can configure the wireless interface via the commandline. If you only connect to one WLAN, then it will be simple, if you intend to connect to multiple WLANS, there are a couple of options.
Before going into the commandline side of things, you may want to try installing wicd, which is a Network Manager esque GUI application that handles configuring wireless adapters fairly well.
Here is a basic guide to setting up wireless via the command line.
And here is a more detailed guide to the same. http://www.linuxhomenetworking.com/w...ess_Networking
For the record, anything that you read that pertains to Debian or Ubuntu, should be compatible with Mint.
Although your WLAN interface name may vary (wlan0, wifi0, ath0, etc)