The difference between the Lite browser and the original DS browser is that they only work for their respective systems. If you have a Lite, get the browser for the Lite and if you have a standard DS, get the standard DS browser.
The only real problem is that the Lite browser is the only one on retail. If you want the standard DS browser you'll have to buy it from nintendo's website. And if you don't already have a wireless router you can purchase the special Nintendo USB port that will allow the Nintedo Wii, DS, and DS Lite to go online. You can find these items
here
As for using the handheld browsers to surf the net, I have not used them myself, but I hear they are, understandably, slower than a PC. My guess is that it would be similar to the Wii browser because it would take a longer time to load screens and sites. But it's usually no longer than 30 to 60 seconds (depending on your connection I suppose).
Another thing to consider is that, unlike the Wii, I don't think you're able to download updates for the browser to view newer flash sites. This may mean that you would have to buy a newer browser down the road if they make one.
I hope that helps, Sparky.
