How do I switch between Gnome and KDE4

I installed openSUSE 11.0 selecting GNOME as desktop, and installed KDE4 later. The installation seemed to have worked. I expected to find a selector on the login screen when I rebooted, but had no such luck. I installed the 32bit version on my 64bit AAMD system having run into driver problems with the 64bit version.
Has anybody a suggestion? Thanks.

If the install was a success by login screen goto session type and choice KDE or GNOME

To clarify: After you boot you are taken to a graphical login screen? And when you click on “Session” at bottom left of the screen, you don’t see any gui choices? If this is the case, for login manager are you using Gnome (gdm) or KDE (kdm)? (gdm has one dialog box where username is entered and then in a second step the password; kdm has two dialog boxes where username and password are entered in one step.) And, having installed KDE 4, have you updated it to 4.1 from the 11.0 Factory 4.1 KDE repository?