@Tiger-Heli,
I understand that it is not your intention to actually use the drive as removable really. I was talking about an hypothetical (but potentially real) situation, whether intentional or not. Windows doesn't care about your intention. It recognizes that disk as removable, and it acts differently towards it.
I don't understand your response on my comment about "all" programs or Avast alone. There are MANY settings regarding the "programs" location in Windows. Changing the default "programs" folder location is not a problem, if you just installed Windows and before installing anything else. Several "tweaking" tools would help you with that. But once you start playing with several programs and with other Windows issues, I wouldn't be surprised to find some inconsistencies or instabilities some time in the future.
So, IMHO, either find a trick to set the new disk as "fixed", install Windows anew and change the default "programs" locations, and only then install "all" your programs to that location, or change the strategy to gain some free space.
I still find it difficult to understand why 8GB of space is not enough for those programs you mentioned. You just need to save your data (not the programs) to a different location. Just to give you an example, if I had to install an email client (not really needed, but anyway), I would install the email client on the default location, but all those massive amount of emails nowadays we daily share and the contact list would be saved on the "removable" drive. Maybe not ideal either, but still better than saving the program itself in a different location.
BTW, several of those programs you mentioned have some portable alternative (either from the same producer or from a competitor), specially useful for "removable" drives and netbooks.
I want to clarify something. Many programs will let you install on "any" location, no matter the current "programfiles" folder in Windows. Those are, generally speaking, not a "big" problem. But some programs are more "sensitive" to those "custom" installations. Your antivirus (anyone) is one of those "sensitive" programs.