Guzman, age 29, is coming off a 2013 season for the Padres in which he batted .226/.297/.378 with nine homers in 126 games. For his career, he owns a solid OPS+ of 110. Guzman is capable playing first and the outfield corners and can man third base in a pinch. Houston GM Jeff Luhnow has indicated that Guzman could platoon with Brett Wallace at first base or win the job out-right (source: Alyson Footer via Twitter).
As for Jackson, age 25, has logged 20 appearances in the majors as a former member of the Cardinals. Across five minor-league seasons, he owns a batting line of .270/.339/.365. While he doesn't have the bat to be an MLB regular, Jackson does grade out as a plus defender at short. He's also played second and third in his career. The Astros claimed Jackson off waivers earlier this offseason.