While you install and configure your shopping cart it is best to leave your checkout page in Test Mode. Leaving your store in test mode will allow you to test your store without the tedious task of filling in the checkout form over and over again.
As an added bonus, if you use Authorize.net Version 3.0 as your secure order provider, placing your store in Test Mode will automatically set Authorize.net into Test Mode as well so you can use a REAL credit card number to test your store without actually being charged. (Always make sure Authorize.nets checkout page actually says the words TEST MODE before testing with a real credit card number.
Test Mode -vs- Going Live
Using Live Mode
Going live with your on-line store involves more than just selecting Go Live from the Test Mode tab of the Checkout Wizard. You will also need to add a link to your on-line store somewhere on your web site.