Yeah, the cooler is quite straightforward to fit. There are detailed step-by-step instructions so as long as you follow them, there shouldn't be any problems. I think it took 10-15 minutes to install.
Mine is fitted on an X1900XTX and the temperatures are a few degrees cooler compared with the stock cooler. When the Zalman is turned right down, you can hardly hear it. When turned to maximum, there's a small whooshing sound which isn't too bad.