If you want to install WSS v3 / MOSS 2007 on Windows 7 you have to made some changes. When you try on a "normal" way, you will fail and receive a big error:

It seems that SharePoint Server 2010 is only compatible with Windows Server 2008 x64. But it's not.
Ok, start up Process Explorer while the installer splashscreen is running and you'll see the following:

So it seems that the installer was unpacked in C:\Program Files (x86)\MSECache\oserver2010. You can browse to that directory now.

• Go to C:\Program Files (x86)\MSECache\oserver2010
• Go to the Files folder
• Go to the Setup folder
• Open config.xml
• Add the following line before the closing </configuration> tag

<Setting Id="AllowWindowsClientInstall" Value="True"/>

Once you've modified the config file, you'll be able to install SharePoint Server 2010 on your Windows 7 machine!
Now you can have your development environment without even dual booting with Server 2008.