I need a synth that can achieve this sound...

Pretty much any of the pad type synths should be able to recreate that sound. I'm mostly a Cakewalk guy myself and I'm sure that Rapture would take care of that sound easily, you could also use something like Z3TA+. I'm sure there are plenty of free stuff out there that will work such as Sylenth1 as has already been mentioned.
 
Sylenth1 is not free. ;) It's a great sounding synth. Rapture is pretty bad ass too.

Whoops - my mistake.

Z3TA+ is now on sale at the Cakewalk store for $19. It's great synth if your willing to really dig into it. Plus you can get quite a few mods for it that all have some great sounds. For less than 20 dollars it's well worth it for it's waveshaping capabilities plus the modulation matrix is absolutely awesome.