The current silverlight 1.0 beta is about 1.38MB (not the 1MB spoken about by Microsoft).
The 1.1 alpha (which includes a subset of .NET) is 4.24MB!
That’s not big for broadband but let’s not be arrogant and assume everyone has that yet.
In terms of competing with Flash, which it does – no doubt – the issue is really about ease of installation. Flash was first installed on systems with Windows 95/98 were everyone has administrator rights. Installation on Vista will be blocked without administration rights which are not granted by default (even to administrators which must temporarily elevate their rights).
Note that Scott Guthrie demonstrationed is ~20 second install on XP SP2, not Vista with it’s “Cancel or Allow” guardian.
Some people may have forgotton that Click Once gives a web distrbution model for full .NET application and the .NET user Controls can already be hosted in IE.
Microsoft must use Windows/Microsoft Update to push through this technology if they want to see rapid adoption, or a good set of compelling applications – is Major League Baseball (a demo at Mix) really that popular with the rest of the world?
Colinizer 
Silverlight is clearly for rich online web applications. That would imply a broadband connection, as anything less would hardly be pleasent for a RIA. So, it hardly seems like an issue for Silverlight to be 4.24MB right now. I’ve seen that MS thinks it may shrink further as well. The current Silverlight 1.1 alpha Safari download for the Mac was about 10MB when I downloaded it last night.
Upgrading to Flash 9 on my Vista machine is no different than the problem Microsoft faces for Silverlight.
Silverlight is cross platform which Click once is not … so I’m not sure I understand your concern. It’s not for everyone, and neither is .NET.
If a compelling web application uses Silverlight — people will download it. I would, and I bet you would as well.
MS is talking about the 20 or second install experience and the 1MB download. No-one has said anything about 4.24MB, curiously. I really don’t see it getting smaller.
Flash is already on millions of machines, so doing an upgrade is not as painful, and there is already a compelling reason present, vs. something that has not been installed yet. Also once it’s installed, the end user doesn’t care if it’s javascript or .NET, but they will care if they have to install something else 4 times bigger just (because the developer wanted the power of .NET).
There are still millions of dial-up users that will feel the pain. I work with a company that has very rich flash-based content and it’s exported for 28.8 users to ensure that many mobile business users can get to it on their notebooks.
Yes I would download it (and have both already), but you and I are likely early adopters.
Anyway, with Windows Update, Microsoft will largely push out at least 1.0 under the radar.
About Half the world (India and China) doesn’t know/care about Baseball. But, I DO expect a lot of traction if they could do that to Cricinfo[cricinfo.com] what they did to baseball, they’ll get a LOT of traction in India. A REAL LOT.
And, as to why the Mac installation is 10 megs, It’s because it is a “universal binary”, which is Stevespeak for “has both the PowerPC and Intel executables”. So, it’s actually two installers inside…
And, if you think about it, the first “real” killer app for Flash were actually casual games. Nobody wanted to see a 20 minute company intro. But, a lot of people wanted to play games, so they’ll install anything to get that. I remember the old pre-broadband days when we used to collect flash Games, bundle the flash player with them, burn them on a CD and circulate them among our friends…
They had/have an agreement for redistributing Flash on CD when it’s bundled with applications (I’ve signed one many times), but you didn’t have an application… 😉