I have the V2 which is really good, best place is ebay, pick em up for around £30 - £45, I was ok at aiming with a stick but really want the mouse feel again and this worked for me.
With online games like MW2 though you gotta have a desk or something in front of you to put the mouse mat on only personal choice mind you, as my K/D ratio went down when it was on my lap, I became more lazy ... (the mouse mat with the v2 and dual sfx is excellent), and only because it's so intense and about quick accurate aiming, single player games are different you can have it on your lap relaxing back
With it I've played fallout 3, far cry 2, Tekken6 (funny but hard work), killzone2 (online kicked ass).
But since i've upgraded to the new Dual SFX Pro wireless, cost me £71 of ebay. Stunning!
It comes with a more weighty lazer mouse. you can also hook all versions up the the PC and redfine the buttons.
Check out this video of DD Dozier using the new SFX.
http://www.youtube.com/watch?v=UCnUokmdq9Q