I did not choose to upgrade Feb CTP to RC0. I installed a named instance (32-bit Standard Edition) on my Windows XP Professional SP2.
The downloaded executable brings with it a folder and number of files.
setup [Native SQL Install Bootstrapper]
Run the setup from a DOS prompt
You may be asked to download the latest Windows Installer
You also need to install Microsoft .NET Framework 3.5 SP1(BETA).
You may have to upgrade your Windows XP SP2 to SP3.
You will then work with the SQL Server Installation Center very much like the previous CTP's
In the SQL Server Installation Center click on the Installation item in the left side and choose the very first item on the right (for my installation) - new installation.
Now just follow the Wizard.
You may need to copy the KEY when you download as it is needed during installation. You may have to reboot a couple of times.
PS: If you follow the readme web page in the download you will be searching for a Servers folder. The instructions are not correct as the instructions for the previous CTP have not been modified.
If everything goes well you should be able to start your server: