We currently run CollabNet Subversion on a Windows server. I recently got the opportunity to move the Subversion server to another machine, and I basically have the choice between a Windows server or a Linux server for it. We are primarily a Windows shop, so I'd probably go with a Windows server with all things being equal, but I was wondering if there are any benefits to putting it on a Linux server instead. I'm not looking for a dispute between Windows and Linux servers, but rather specific features, documented performance differences, or any other reason I might prefer Linux for the Subversion server.
Our clients use TortoiseSVN, and, if it matters, the server versions would probably be Windows Server 2008 R2 or Ubuntu 10.04, but this is probably flexible, too.
Edit: A few extra comments after some answers: the licensing isn't an issue for us for this, our VMWare cluster has plenty of spare resources, so that's not much of an issue, and I'm comfortable with both Linux and Windows, so that doesn't affect this either. It sounds like I'm hearing there isn't a difference though, so that might be my answer.