I got my DS Lite today! I haven't really cared much for it, but I have decided that it is WAY cheaper than the PSP, so I might as well go for it. Plus, I got a router, so I can play online without that USB connector.
My brother got one as well, so we can play eachother whenever we feel like it. We got Mario Kart DS and New Super Mario Bros, both very fun games. I can't wait to play online with other people over the router.
I'm planning to get Advance Wars for the DS and many other games, but that will have to wait a while. Once I start to refferee in the fall, I can buy a few more games for it.
If you're looking for a new handheld, go with the DS Lite, its better, cheaper, and just as fun as the PSP!