SuSE11.1, I can download software but it doesn't install. The Yast window opens and all seems to be going well as the download progress bar advances, but at 100% download all progress stops. The install progress bar remains blank. I tried downloading google earth and AVG antivirus for linux but neither installed.

Where did you download it From ?
From the opensuse side ?
Or from the AVG en google side ?
Which did you download tar yum rpm ?

I went to the google site and clicked on the download button. Same with AVG antivirus. it seemed to be downloading fine, the progress bar moved along normally, but after it reached 100% nothing more happened. The Yast window just sat there motionless and the "install" bar refused to budge.

Google Earth: I successfully installed Google Earth by downloading the .bin file and just running it. Note that it is a POSIX shell script which contains text and binary data and not a RPM package. You can think it as an auto-installer. In other words you cannot use the Yast Software Manager application, since it manages only RPM files. Here is a quick howto (that is how I installed it on opensuse 11.1, last February).

AVG antivirus: I leave to other members to question about the usefulness of an antivirus software in Linux. Anyway, since the downloaded RPM has not been built by opensuse, better to test it from the command line (so that you can read what's going on directly from the terminal).

Using the rpm command, you can first test the installation, without actually install it:
if you see simply the progress bar and no error message thereafter, you can proceed with installation. This means that all dependencies are satisfied.

However, at the command line you have a more complete and suitable software manager: zypper. The command
will ask confirmation prior to install and it will give messages and advices if something is missing or wrong. Feel free to post them here, if in doubt.

Good luck!