no, but the stock one just sucks. For the SI-128 and most Thermalright heatsinks, they include clips to clip on the heatsink. http://www.newegg.com/Product/ShowI...MALRIGHT+SI-128+CPU+Cooling+Heatsink+-+Retail If you look there, its the second one from the left. Those are the clips. With the SI-128, the fins are very dense, so i suggest using a fan with high static pressure to get the air though the fins. Delta triblades are very suitable for the job, as are Sanyo Denkis.
Like Ownage said, ThermalRight includes clips to hold the fan onto the heatsink. My SI-120 came with them, and included these rubber pads so it'll cushion the space between the heatsink and fan.
You'll need thermal paste anyways, but ThermalRight includes a tube of thermal paste. If you want to get better temps, buy a tube of Arctic Silver 5.
Would a third Smart Fan II work? The air flow isnt as high as the Delta (141 @ 3700rpm vs. 95.22 @ 3500rpm) but it would save me money on the fan and getting a controller. This way I can run the front and back at 50%, the side fan will work at whatever speed it works at (Ill leave the stock one, theres gonna be a ton of air flow), and Ill put the one sitting over the heatsinker at about 75%. The only downside is there will be 3 separate controllers, I might have to see if I can create something.