I'm importing a TLB file into my project since I'm using a COM DLL. A TLB file is a binary file, which I need to compile my source code and so I was wondering if it's good programming practice to commit it to the repository.
Yes, it's ok to put binary files in a source repository. The rule sometimes called 'do not put binary files in a source repository' should better be called 'do not put temporary files or files that are a compilation result in a source repository'. Basically anything that can't be produced from other files and is relevant for the project itself (i.e. no editor preference files) can be put in a repository.