Ask HN: Which revision control system?

For the past few years we've been using Perforce at the company I work for. For a number of reasons, we've been given the OK from management to switch to a free SCM system. This is supposed to be a big opportunity to improve our process and save us money, but we're having problems finding a good replacement. Our must-have features include; ability to import our perforce history, easy/trivial branching and merging (preferably the ability to use an external merge tool), large file support, ability to pass changes from one workstation to another without affecting everyone, and ability to work with multiple gigs of binary files (most are roughly 500k, some are 100+megs). The binary files are mostly build artifacts, but for a large number of very good reasons we can't expect developers to generate them. Each developer having their own branch would be nice, but isn't critical. Our products only run and compile on Windows, so decent windows support would be nice. We aren't exactly an MS house