Well, it's a bit complicated and you may take a tax hit if you withdrawl your account completely. Are you close to retirement age? What tax bracket do you think you'll be at when you retire?
You can read more about conversions here:
http://www.rothirarules.net/
http://ww.rothirarules.net/roth-ira-tax.htm
http://www.rothirarules.net/roth-ira-conversion.htm
Good Luck