A lot of people say their predictions as to which system will win this current generation (I am one). However, some people refer to consoles of the past to justify their answers. I will say the most common references people say and I will correct them
*****Sony fanboys say that the 360 is like the Dreamcast. The dreamcast was released earlier, had more games, costed less, but still managed to get its A$$ kicked when the PS2 came along (PS2 being the PS3 in this case).*****
WRONG. For one, Microsoft is many times more rich then SEGA will ever hope to be. Thanks to Microsofts plentiful supply of cash, they have secured exclusives, making exclusives cross platform onto their console, and have acquired many developers as exclusively working for them. SEGA could never do what Microsoft is doing now with money.
Dreamcast graphics were terrible. PS2 games were less blocky and more realistic. The PS2 controller looked and played much better then the Dreamcast controller did. Now, the 360's games look on par and in some cases look slightly better then the PS3 counterparts (at least for now). The 360 controller also feels and operates better then the Sixaxis (its true, deal).
Dreamcast was hacked like nobody's business. Software sales were next to nothing. That's the main reason why it failed. The 360 has done a good job of not being completely hacked yet.
I will add more examples as I hear them. ***Feel free to tell me some improper referencing examples you hear people use***.