We have developed a .NET assembly, which we call SCA.NET, which we have been using for building EPICS based control room applications at the Advanced Light Source (ALS). In this paper we report on our experiences building a 64-bit version of SCA.NET and the underlying channel access libraries for Windows XP x64 (using a dual core AMD Athlon CPU). We also report on our progress in building new accelerator control applications for this environment.