Can I introduce the SteelSeries Siberia USB Headset? can be had around £60 at usual computerstores or cheaper online.
Basically the PX1 is a usb soundcard to give a line in to the mic and you connect your headphones to your tv or phonocables from PS3 through a 3.5mm.
The SteelSeries Siberia USB, made by those guys who make Icemats (make sure it says USB on the box!) is exactly the same solution. USB soundcard for line in and headphones, which sound fantastic and look really good too (if you care about that stuff). Its seems pretty darn well built too.
THE advantage of the SteelSeries is that the Mic is a clip type, and is mega sensitive, so you can clip it anywhere on you or the headphone cable, I dont like people hearing me eat lol! The mic is on a totally seperate wire which clips all the way along the headphone cable or you can just seperate it if you like like I have done and it has a little velcro attatchment thing so its clipped onto my desk permanently.
Like the PX1's you can buy the xbox 360 thingamajig to make the mic work with the 360.
I sound like i'm trying to sell them myself but I just think they're awesome, and work simply with my xbox ps3 and pc