Well to be honest if you want to use Visual Studio, I suggest you use windows in a VM or dual-boot. Even if you manage to install visual studio in a Linux machine, without the liblaries and .Net Frame work you wont be able to run the aplications you create from visual studio
Oh the other hand I think it would be better for you to use a web based or platform independent visio alternative than dia. My suggestion is to use a better visio alternative working with any browser.