The grades of three Software stocks are on the rise this week on Portfolio Grader. Each of these stocks is rated an “A” (“strong buy”) or “B” overall (“buy”).

Vringo Inc. (AMEX:VRNG) is making headway this week, with the company’s rating improving to an A (“strong buy”) from a B (“buy”) last week. Vringo provides products for mobile video entertainment and personalization. For more information, get Portfolio Grader’s complete analysis of VRNG stock.

Citrix Systems‘s (NASDAQ:CTXS) grade is moving up to a B (“buy”) this week from last week’s C (“hold”). Citrix Systems designs, develops, and markets technology solutions to deliver information technology services on-demand worldwide. The stock price has risen 5.3% over the past month, better than the 3.1% increase the Nasdaq has seen over the same period of time. For more information, get Portfolio Grader’s complete analysis of CTXS stock.

Fair Isaac (NYSE:FICO) earns an A this week, jumping up from last week’s grade of B. Fair Isaac provides analytics, including predictive modeling, decision analysis, intelligence management, decision management systems, and consulting services. For more information, get Portfolio Grader’s complete analysis of FICO stock.

Louis Navellier’s proprietary Portfolio Grader stock ranking system assesses roughly 5,000 companies every week based on a number of fundamental and quantitative measures. Stocks are given a letter grade based on their results — with A being “strong buy,” and F being “strong sell.” Explore the tool here.