As of June 18th, 2001, Microsoft officially released Beta 2 of the .NET Framework SDK (of which ASP.NET is part of). To download this beta, visit http://www.asp.net/. The official release of ASP.NET v1.0 should (hopefully) be out in the September/October/November timeframe of 2001. (Read Scott Guthrie's (the cocreator/lead developer for ASP.NET) official announcement here.)
Unlike the first ASP.NET beta, which was ~120 MB, ASP.NET Beta 2 is a mere 19 MB. This second, smaller beta was packaged to benefit downloaders with a slower connection and was made smaller by excluding the documentation, samples, quickstarts, and other unneeded portions that were part of the Beta 1 download. Don't worry, if you want to download the complete package, you can do so here (be warned, it is ~135 MB).
The .NET Framework SDK is designed to run on Windows NT, Windows 2000, and Windows XP, however, the 19 MB ASP.NET beta download will only run on Windows 2000 or Windows XP (both server and workstation editions). It will not run on Windows NT 4.0. While you can develop ASP.NET applications on Windows NT 4.0 just fine, serving ASP.NET Web pages from Windows NT 4.0 won't work. (For more info be sure to read this article.) Also, you'll need to have at least Microsoft Internet Explorer 5.01 and should consider installing MDAC 2.7 (a 5.5 MB download). (MDAC 2.6 is the minimunm requirement; MDAC 2.7 offers additional functionality, but is not required.)
One neat thing with ASP.NET Beta 2 is that Microsoft has now made it (legally) possible to run a live site using the ASP.NET beta builds! (With Beta 1 you needed special permission from Microsoft to run a live Web site using ASP.NET.) To use ASP.NET Beta 2 to run a live Web site, simply sign up and fill out a few forms at http://beta.visualstudio.net/.
There are a plethora of syntactical and technical differences between the two betas. A complete listing of these changes can be found in the .NET Framework SDK Late Breaking Known Issues article. As always, with any Beta software version be sure to install the software only on non-mission critical computers. Microsoft warns: "Install the .NET Framework SDK Beta 2 only on computers that are not used for production or mission-critical data."
There really is a ton of useful information in the .NET Framework SDK Late Breaking Known Issues article. Be sure to read over the first couple of sections very carefully before deciding to install the Beta 2. Also, once you install Beta 2, that article should prove invaluable in pinpointing changes and errors.
There have also been a wide array of syntactical changes in the .NET Framework classes. For example, the way you work with ADO.NET through an ASP.NET page has changed, in syntax, quite a bit from Beta 1 to Beta 2. Fortunately, the .NET Framework Documentation contains ample explanations and examples in both C# and VB.NET. The good news is that Microsoft predicts that there will be no syntactical changes from this Beta 2 to the final release of the .NET Framework! For a very thorough and complete list of syntactical changes from Beta 1 to Beta 2 be sure to check out this article. (There are a ton of changes!)
If you've already worked with ASP.NET Beta 1, moving to ASP.NET Beta 2 will involve only brushing up on some syntactical changes. (There are some new classes / namespace name changes / etc. that will take a bit more time, but nothing drastic.) If you haven't had an opportunity to work with Beta 1, feel free to get started with Beta 2, since code produced in Beta 2 should require no tweaks when the official release of ASP.NET comes out.