Forum:Puzzle Maker / PTI

I own Portal 2 for Xbox 360 and I re-he-heeeaaally want to try out the PTI. I know it's PC/Mac exclusive, so my question is: Do I have to buy the PC version of Portal 2 to get this free bit of DLC, or can I just get a demo? Even better, is there a standalone version of PTI (I know there's Hammer but that's a but too much)?

If I have to buy it over again then I won't bother; my laptop would struggle playing Quake 2, let alone Portal. Plus I've already bought it once, and PTI is free.