I just went through this with a recent site I built for a client, the designers used Helvetica. It's supposed to come on Macs. They also say it comes with Adobe products, but I don't have it with CS5.5 Design Standard.

It is just a sans-serif, so I would honestly look for a free alternative. Google Fonts has plenty of sans-serif to choose from.

Borghs Crack Fonts Downloads For Mac

Here are some suggestions from TypeKit, but I'm not sure if any of them are free. I ended up making this client purchase a TypeKit subscription. You can also try these that should be on Google Font.