I finally managed to get the installation working. The problem I had before was that I didn't manage to uninstall the noveau video driver that openSuse 11.4 was using.
On the nvidia driver download page, I finally found an additional information tab which had a link to a howto for suse users. That howto explained that there was a software repository at download.nvidia.com (/opensuse/11.4) that could be used instead of the .run file. Then I installed the packages the usual way using Yast.
Then I rebooted to get the old driver out of the kernel. After that I installed the GPU Computing SDK. When compiling the examples included I had the same problems again (mentioned in the first post) regarding gcc-4.5 and solved it just as Christenson suggested. After creating a missing link
Code:
libglut.so -> libglut.so.3
in /usr/lib64, I managed to compile enough of the tests for the SDK to verify the installation (though it still failed missing mpi.h later).
The documentation file at Cuda Toolkit, CUDA_C_Getting_Started_Linux.pdf, was also very helpful.