Haha... rampant fanboyism in this topic.
Sadly, people forget that you can't compare the two handhelds. They were designed for two entirely different groups of people, and were made to serve 2 entirely different purposes.
DS- for gamers, designed to revolutionize handheld gaming
PSP- for tech freaks/rich people, designed to make them money
Yes, the PSP has a craptastic battery life, but it also has better graphics and a bunch of other features to make the problem worse/distract you from it.
Overall, for extended gaming, which is what Tom would need in this situation, the DS is better, unless he wanted to carry around a couple spare battery packs with him everywhere, while praying the disc doesn't eject, causing a huge mid-air disaster.