The metal studs are probably 12 gauge at best. A regular bit will go right through them just fine. I am currently using E-Z Ancor Twist-N-Lock dry wall anchors to hold up a pair of 15lb speakers.. They are working just fine and have been for the last 2.5 years.
Here is a link to the product that i am using.
http://www.lowes.com/pd_71529-2191-11364...&facetInfo=If you do decide to go into your studs, do what nick said, use self taping screws, this will eliminate the need for you to drill a pilot hole into the metal.
Good luck.
