I have an SMS 2 / Win2k environment and have been very pleased. I have not tried Network Discovery, however.
As far as logon discovery and installation, that's absolutely no problem in Win2k! The exact same logon script options are available in the Win2k domains (user assigned logon scripts), and now includes a very nice new method: Group Policy (GPOs).
With GPOs you can "assign" the client installation to users or machines. This means that the client agent is required to exist for the user or machine objects! Client integrity never had it so good!
Another cool new feature using Win2k is on the SMS Site Server. With Win2k, you get WMI Control (a new Computer Management application) installed in your site server's Computer Management MMC. This applet allows you to view and edit your WMI security on the site server.
Although SMS 2 SP2 includes a wizard to configure WMI security ("Manage SMS Users" on the right click menu of the security node), which pretty much solves the old WBEMPERM issues, this little applet is sweet to have and only installed with Win2000.
Generally, Win2k is a lot better because it installs WMI 1.5, which gives you a lot of extra information and features.