What source control should we use

Question

I am looking for a good source control solution. Here are the requirements:

1. Must have a GUI or have an available GUI plug-in.
2. Must be free.
3. Must work with HTTP.

What source control would you choose?

BACKGROUND

Our .Net development team is part of a large parent company. We're in the process of acquiring VS Team System, however the bureaucracy of a large company moves slowly and it could be months before we have a Team System server up and running. In the meantime, we have a large project that will be outsourced to a vendor in India. In the past, our team's process has been something like this: 1)specify the requirements, 2)let the Indian team create the solution, and 3) receive the solution back from the vendor a month later.

We're looking for a more disciplined approach and Team System is our long term solution, however I'd like to use something right now instead of nothing.

Here are some of my thoughts:

1. Source Safe is a no-go, because of stability issues.
2. Ease of use is more important than advanced features, like branching and I'd really, really want it to use a GUI versus command lines.
3. HTTP access is a must, because the development team will be remote.

Additional Information as a follow up to feedback so far

We need a free solution, not because we can't afford it, but because the company's corporate purchasing policies will delay getting it. Free enables us to install at any time. I suppose that if it were cheap enough, I could pay out of my own pocket, but it would have to be pretty cheap.

Final

Sadly, we did not end up using any of the recommendations. We did finally obtain a TFS license, however we're not expected to have clearance to use the server until next year. In the interim, the offshore team is uploaded zip files onto an ftp server. Ugggghh! Why is it so hard to convince large companies that it's ok to use non-standard solutions (such as GIT) rather than wait months (or years) as they dither on trying to decide whether or not a purchase (in this case TFS) is worth it.

Answer 1

I recommend Subversion and TortoiseSVN. Even the documentation for Subversion is free.

Edited to add: I also strongly recommend VisualSVN Server to setup your SVN repository. The setup was a snap and its been so trouble free I had to go look to see what it was called because I haven't had to touch it once since the initial set-up.