As a newly born .NET/C# developer, I have trouble finding those must-have-tools. At my current job, they are running VS2005 in a huge system with over 70 seperate components/solution files with each having around 2000-10000 LOC. This gives me a huge headache as it takes forever to build, and everything is built with batch files. (so 90-ish)
But as a java developer, I have come to love Ant. There is a .NET version of it called NANT that I downloaded and was going to test and hopefully replace the batch files. 10 mins after downloading I stumble into the first problem. NANT does not support (as of 25 aug 2006) Visual Studio 2005. NANT can not handle the new solution files as they have change completly (not surprisingly). Apparently it is quite a job to add VS2005 support, so it seems that it is not going to happen. So NANT is definetly not ant, as it will probably cease to be used.
The new king of building MS code is MSBuild, which seems to be a total rip-off from Ant.