Rep alone is a great start but not the final checking point. When installing apps recomended even by the reputable (yes, who reccomended it to them?) you should also do your own research, for example, Google query of : Appname + trojan, to start with. Also, if the app requires admin rights to install or execute (even in the case of a portable app), then the best practice is to install it sandboxed with network access disabled. Actually if its not intended as a network app, sandbox it or firewall it regardless. Since Windows 7 has a lack of decent lightweight firewall, sanbox may be the best bet for many here.