If it is a hot night, then consider some form of cooling, the sensor gets hot and noise becomes an issue.
Can you post a RAW image somewhere? What ISO were you shooting at, and how long was the exposure?
Are these the jagged trails you meant with the software?
http://www.flickr.com/photos/6638216...n/photostream/
The jaggies can be as a result of having VR/Image Stabilisation turned on, or the tripod being to lightweight.
As for the noise, I make sure the camera starts off rested and cool, and set it to ISO 200 and try a 10-15 minute exposure. Turn the camera off for 30 seconds to cool the sensor back down and then take another 10 minute one. Seems to work okay and be low noise.