Can I get viruses with the downloadable software?

This is highly improbable. The online gambling venues aim to attract more customers, not to drive them away. Given the intense competition in the sphere of online gambling today, no casino or poker room would take the slightest risk of including something like a virus in their software as this would ruin their reputation in the long term. For your safety, you should of course scan all programs you download from the internet for viruses.