I think they're both ATi and lol, did you guys check out the new ATi website? Talk about total integration with AMD, damn. I would pick the X1300 because I don't know anything about the express 300 besides being the fact that it's an integrated video chipset.
Id have to say the x1300, because the 300 comes in most dell computer and it sucks balls to my opinion...Also the x1300 core clock is alot higher, go with the x1300.