This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
A "legacy" class, or method, or system, means something that you're stuck with from the past that, if you could start over from the beginning, you'd get rid of. The Vector and Hashtable classes have been superseded by the newer, better ArrayList and HashMap classes, but Vector and Hashtable are still supported so old code can run. But you shouldn't use them in new code.