I just got my new Nintendo Power, and there was an article aout Mario Party 5. The most noticeable changes:
-You can be Toad, Boo, Koopa Kid
-You can't be DK, he has his own space(like Bowser, but good)
-New mode in which you must construct a kart/tank hybrid (out of Mario-themed parts) that battle other karttanks
-New Volleyball and Ice Hockey Games
-Toad no longer gives out stars, the Seven Star Spirits from Paper Mario do.
If anyone wants to post the information I left out, feel free to do so.