How do I get sony Vagas pro 9 full verison without getting a viirus on laptop? PS i need 32 bit?

I want to download sony vagas. But when I tried to do it it put a virus on my laptop. I used to use Windows Movie Maker, but that's crap now. Can someone please tell me how to download the full version of sony vagas pro 9 32 bit without getting a virus on my laptop again?|||You buy it.