I'm looking for the best headsets for PC gaming. Is it safe to assume Astro and Turtle Beach are a good start since they are the best for console gaming?

For anyone who has an Astro headset (or knows the answer to this question), what is the A40 MixAmp and what does it do for PC gaming. I read the information on the Astro Gaming website (http://www.astrogaming.com/products/detail/4/A40-Headset/) but I wasn't too sure what it is, what it does for PC gaming, and if it's necessary.

In regards to Turtle Beach, I saw two potential headsets: USB PC Gaming (http://www.turtlebeach.com/products/akr8/home.aspx) and Professional Gaming (http://www.turtlebeach.com/products/efhpx/home.aspx). What's the difference and which would I go with for PC gaming.

Thanks.

I forgot to ask: if I get one of those headsets, then will I need a sound card?

Since the Astro is not a USB headset, you'll probably want to get a high end sound card for it to get the best possible sound from it.
Personally, I would go with the USB Turtle Beach headset, because then you won't need a good sound card to get good audio quality, and it has surround sound built in, which the Astro does not.