I agree with Dark Shadow
What do I mean Dreamcast looks better than PS2? Developers have had problems for years with anti-aliasing for the PS2 because its so difficult to develop for just like Dark Shadow says is going to happen with the PS3. Also the PS2 isnt any more powerful than the Dreamcast when it comes down to it because it was easier to make better looking games, even current gen PS2 titles still dont look as good as games like Resident Evil Code Veronica on Dreamcast.
Frankly we wont know if PS3 or 360 will be more powerful untill both of them are released because they just keep throwing numbers back and forth without giving us alot of facts. Things like the unified pipeline are true but whether that means more power we dont know, also Sony's machine wasnt completed that long ago so who even knows about any of that either.
I think whichever company has the best online service will make a major difference as well, Xbox had a big positive over Sony and thats Xbox Live.
One thing Sony had over Xbox was its RPGs, but now Square Enix is putting its Final Fantasy series on 360 along with the Japanese companies bought, so what Sony had over Microsoft is gone. The only games I can think of that Sony would still have would maybe be God Of War and Katamari to make sequels for in terms of franchises, or Ratchet and Clank.