I'm playing around with this thing right now on my midi keyboard, and I have to say, it sounds beautiful for a free vst. Right off the bat it loads up a fatass supersaw lead. It comes with 3 oscillators with six waveforms to choose from (including a supersaw made up of 7 detuned saw waves). It comes with plenty of built in filters and effects perfect for trance and lots of other styles. I used this in my most recent single and it fit in beautifully with other more expensive synthesizers.
So go get your hands on a VST host of some kind (there are freeware ones out there) and give this beast a try. (Download links below!)