Forget about the Game browser, I never used it. Some games don't even appear in it. Never used it in the 4 years of contact with it. I just disabled it.

Microsoft does have its own free anti-virus as well.

I will tell you now, for the love of everything, do not install games/steam/etc in programs. Do a folder on the harddrive you have your games on, called \Games\, for example, "C:\Games\". Other than making it very easy and helpful you have your games separate from your programs, it will save you lots of heartache, due to inbuilt Microsoft security.