The classic version is also known as WindowBlinds version 4.6.

It can be installed via "Stardock Central", which is a program you download here https://www.stardock.com/products/sdcentral/

I know that if you purchase WindowBlinds 5, you would then have the option of downloading and installing either version 5 or 4.6.

I believe, though it has been a while, that the 4.5 version is offered as a "demo" version if you have not purchased anything and just install Stardock Central (a program which acts as a central hub for Stardock Products by contacting the Stardock servers, as well as having web browsing, news links, and IRC chat channel access). This program does not run in the background, and only attempts to contact the servers when loaded. You can set it to work "offline" via the File menu, but this will not allow downloading of the products. You can however, restore archived applications while set to offline, if they do not require activation - which 4.5 or 4.6 do not.

Note - I am not sure whether 4.5 has a time limit or not, but if it is version 4.5 and not 4.6 - the main difference (if memory serves), is that 4.6 supports some transparency in the start menu. Both versions should work on Win2000.

I just noticed, if you go here https://www.stardock.com/products/windowblinds/downloads.asp and mouse-over the small 'WindowBlinds Classic' text in parenthesis after "Requires: Windows XP", the text will become a link which when clicked loads the classic version download button.   

Sorry if you already went through the trouble of installing SDC.  

Edit: If you installed Stardock Central (SDC), have no other Stardock products installed, and want to remove it completely - simply use the "Add or Remove Programs" function in the Control Panel > select the "Custom" method > click all subsequent "Select All" buttons to select all files in dialogs > click Finish to complete the uninstallation.

This will uninstall all files with the exception of a couple of registry keys under the "SOFTWARE" keys, which really are harmless if left.