Did you use the NEW ITEM process to be sure your editing sequence and your video match?
CS5-thru-CC PPro/Encore tutorial list http://forums.adobe.com/thread/1448923 has NEW ITEM links
Some of this is from the Premiere Elements forum, but the idea of sizing pictures is the same for PPro or Encore
Pictures that are "overly" large may cause video editing problems
Photo Scaling for Video http://forums.adobe.com/thread/450798
-HiRes Pictures to DVD http://forums.adobe.com/thread/1187937?tstart=0
-PPro Crash http://forums.adobe.com/thread/879967
You do not mention what you are editing? (what media type, how many layers, what color correction, timeline size, jpg sizes, effects, any 3rd party filters, etc.)
Here are some general thoughts and some more helpful ones may follow if you tell us more about what you are editing:
- try reducing the playback resolution
- reduce the resolution of the JPGs prior to importing them into your Premiere timeline
- your PC is super-fast; a stronger PC can do more without requiring rendering; you can monitor your cpu usage, RAM usage, and GPU usage to see what is likely limiting current playback performance and if none of those are maxi'ing out, the you could be disk I/O bound for what you are doing
What size were those JPEGS?
Your nVidia Quadro 600 is a real weaking for using MPE GPU acceleration and depending on the size of your JPEGS you might require more that that cards 1 GB of video RAM.
Also your 8 GB of RAM might cause problems.
What is your disk drive configuration?