The unexpectedly sharp rate cut by the Reserve Bank helped lift the Sensex at the Bombay Stock Exchange a good 207 points, or 1.2 percent, to 17,358. Positive European markets also gave a fillip to investor sentiment. The Nifty at the National Stock Exchange rose 64 points, or 1.2 percent, to 5,290.And the stock market rally, along with dollar selling by exporters, led to the rupee gaining 20 paise, to close at 51.47 against the dollar.