While Google continues limited beta tests of its new Gmail service, which offers one gigabyte of online storage, Yahoo has gone the search king one better, offering two gigabytes of storage to subscribers to its premium e-mail package, up from 20 megabytes. Users of Yahoo’s free e-mail service, meanwhile, will get 100 megabytes of storage, up from 10 megabytes. At the same time, Yahoo has streamlined its Web e-mail interface and says it has given the software and servers behind the system a major tune-up, improving speed and searchability. (Search Engine Watch has a useful report on the change.) With such large amounts of storage at hand, Yahoo mail users may have less reason to switch to Gmail, although Yahoo mail stil lacks certain features of Gmail, such as the ability to display threaded e-mail conversations.