Bell, a former starter in Denver who had just 45 yards rushing in the past two seasons, is vying to be the Saints' third running back. On Saturday he and Pierre Thomas split time with the first team while Bush was out with a strained calf.
Drew Brees was 9 of 14 for 87 yards and a touchdown after missing three days of practice last week to attend his mother's funeral.
Houston's Andre Johnson had four receptions for 38 yards and New Orleans receiver Marques Colston had six receptions for 66 yards.
Matt Schaub threw an 8-yard touchdown pass on the Texans' first drive. Houston's starting offense stalled after that and punted on both of its other possessions. Schaub was 11 of 16 for 97 yards.
Thomas has a 9-yard touchdown reception from Brees on the Saints' first drive. He got ahead of Houston's defense and grabbed the ball to score untouched.
On the play before that, Mario Williams got a sack taken away when the Texans challenged the ruling that Brees was down by contact before the ball came out. After reviewing the play, the officials ruled that it not only wasn't a fumble, it wasn't a sack either, but simply an incomplete pass.
A high point for Houston's starting defense came on the Saints' second drive. Linebacker Xavier Adibi hit Devery Henderson as he tried to catch a pass inside the 10. Henderson couldn't hold on and the Saints had to try a field goal.
They came away empty-handed after the first kick was nullified by an illegal formation penalty and the second one sailed wide left.
In the second half the Saints added a score on a 79-yard punt return by Rod Harper. Harper played for the Arkansas Twisters of the af2, the developmental league for Arena Football, before signing with the Saints in June.
Joey Harrington, who came in for Brees with about five minutes left in the first half, was 8 of 15 for 69 yards. Mark Brunell took over early in the fourth quarter and was 5 of 6 for 96 yards.
Adrian Arrington had three receptions for 77 yards for New Orleans.
Houston's Dan Orlovsky was 11 of 17 for 136 yards with a touchdown, an interception and a sack. He found Andre' Davis on a 23-yard touchdown pass in the third quarter.
His interception came just before halftime and led to a 22-yard field goal by Garrett Hartley that put New Orleans up 17-7. Saints linebacker Anthony Waters sacked him and forced a fumble in the third quarter.
Houston's Alex Brink was 5 of 8 for 38 yards with an interception in the fourth quarter.
Herb Donaldson had a 14-yard touchdown run and P.J. Hill added a 1-yard score for the Saints in fourth quarter.
The Saints played without starting left tackle Jammal Brown, who is out with a groin injury.
Houston rookie tackle Cliff Washburn left the game with a strained left calf.