No for Windows there is only 1 CD, can you see a Windows Installation Server listed in your Clients ->Installation Servers. If so you could remove it and then try the Install Again.
When you start the install on the Windows Server are you prompted to install either a Cell Manager / Client / Installation Server?
Is the current Cell Manager the same as before just upgraded to 5.5 or is it a new server name? You may need to find the cell_server file and delete its contents on the client or find in the Registry the Cell Server key and delete.