30d user here. actually u cant compare alpha a100 with eos30d side by side. 1st of all, in terms of pixel number, sony alpha is 10mp while 30d is 8.2mp. they are using different technology for the sensor, canon uses CMOS while sony uses CCD. u can always google for the comparison of CMOS and CCD. continuous drive in 30d is much better than in a100 (30d 5fps up to 30 jpeg, a100 3fps only), for professionals or semi-pro, this feature is a good combo when purchasing a DSLR.

but the a100 is definitely better than 400d for some reasons.
u can read it here. http://forums.dpreview.com/forums/read.asp...essage=19761494