How do I verify whether or not software is legitimate and will not corrupt my PC with viruses?
Hello, another possibility is installing an antivirus like Avast that provides sandboxing. It will open by default when you are installing a new program. You can decide whether you use it or not. Also Comodo firewall provides sandboxing for running new applications/programs. The most important habit you can get into, is scanning any file that you download, either by using your antivirus or checking it online like one of the previous posters mentioned.
An alternative for a sandbox environment as Jeff explained would be an actual Virtual Machine - setting one up will take more effort than sandboxing so this is rather a suggestion if you already have VM running somewhere.
Personally I also suggest to use some Web of Trust extension or Add-on for your browser. This should also help you to identify if a site (and downloadable software) are rather safe or should be handled with care.
The non-tech way of doing this, is to upload the program to an
online malware scanner. Virus Total and Jotti will scan the file using multiple engines to ensure the accuracy of the result. You should research the results (or ask here) of the scan, as sometimes the scan will yield false positives. Where possible, download the copy from the authors website. You may also run the application in a "sandbox", which is a virtual environment whereby the execution of the software does not jeopardize the rest of your data. A good sandbox application is Sandboxie.
Use google to review, search reputed sites.
Read reviews of a software before installing on web.
I trust http://www.softpedia.com,
If it says the software is clean then it is clean.
they provide really nice freewares that can make your life easy.
cnet has featured some software which were detected as virus dont trust them.