What are the chances for Spring admission?

[ahmed4]

I would like to ask if anyone knows about the chances of applying in Spring, how does it differ than Fall?, I know that Fall has the highest number of applications and also the number of available positions (RA,TA,fellowships), but what are the other factors affecting the chances, like the ratio between the number of applications to the available positions, is it still better for Fall?
Does it depend also upon the univ, in other words, do some universities take many students while others take few ones? (already not all univ have spring admission).

I think of applying in Purdue and CMU (ECE dept) for Spring 2007, anyone know special details about them for the spring admission?

Ahmed