Short answer: I think this is almost inevitable because, however hi-spec your system may be HD WMV files are going to be pretty demanding in terms of "real-time" playback/editing.

As I understand it, just as with AVCHD files, HD WMV are compressed files and hence require decompression to take place in order to "play" them.  IOW MEP or VPX must stream the files from your hard drive, decompress them and send them to the video output of your computer in "next to no time"!

However, two things you can do to help improve this situation: lower the resolution of the on-screen playback to "half" or even lower.  THIS HAS NO EFFECT ON THE RENDERED FILES (i.e your final output, whatever that may be) but does enable "smoother" playback for editing, albeit with some loss of video quality on the timeline.

The other "solution" is rather more expensive: the new VPX5 can automatically create "Proxy" files (lower resolution "copies" of your original files); it uses these Proxy files for timeline display/editing etc. but creates your final output from the original HD files.  Having just bought VPX5 I'm looking forward to testing this new facility with AVCHD files, which I quite regularly deal with; attempting to edit in full resolution in VPX4 would always create the stutter problem.  Hopefully this new facility will enable a more "stutter-free" editing experience.

Jeff

This drove me crazy for the longest time.
What happens is if your computer does not capture the frames as quickly as it should, the framerate will be slower and the audio will eventually lose sync as time goes on. Download WinFF and increase the framerate slowly until you notice everything is still synced at the end of the movie. I had to increase the framerate to 32 and then everything was 100%. You will know immediately after you load the movie into Movie Edit Pro. You will get an idiot box come up on loading the file and ask you if you want to change the preview box to the information of the file - THE ANSWER IS YES YOU DO. Now jump to the end of the move and see if everything is lined up. If it is, everything will be 100% from then on for that movie.
Once it matches up in the preview it will also burn correctly.

I did find that when using the record option in the program itself, the framerate was 100%. It also shows you if any frames are being dropped. Oh by the way, when you are recording - LEAVE THE COMPUTER ALONE. DON'T START SURFING WHILE YOU WAIT.

Here is how to do it.

OUTPUT DETAILS - DVD/NTSC DVD FAST (LQ)
VIDEO - enter your video bitrate/frame rate (32 in my case)/video size/aspect ratio
FFMPEG - ENTER THIS (INCLUDING THE DASH)     -async 10

(now a note on other DVD CREATION SOFTWARE) Sometimes all you need to do is change the async value  to 10 and not the framerate and the DVD will work right.
 

Sorry, but I think this has nothing to do with the problem the OP has raised.  He/she is talking of stuttering playback whilst editing, nothing to do with capturing footage or rendering to final output.

Sorry I may not have been as clear as I should have been. The problem that I was having was during the preview playback in Movie Edit Pro, immediately after importing a mpg file, and not during capturing or rendering.

I am new and will try better in the future.

Sorry I may not have been as clear as I should have been. The problem that I was having was during the preview playback in Movie Edit Pro, immediately after importing a mpg file, and not during capturing or rendering.

I am new and will try better in the future.

No need to apologise; I think you explained your problem very well.

Have you read/tried the suggestions mentioned in my previous post (three below this one)?