Exporting my 720p video = misery!

I'm really struggling trying to get a decent output from my Premier Pro (CS4) project. I would like to export the project as a H.264/MP4 file, but just about every media encoder configuration I have tried results in video playback which isn't as smooth as I am expecting.

My project is a 1280x720p 30fps (square pixel) video, which I want to encode as the same. I've even tried going up to a video bitrate of 35mbps with pretty average results (see settings below). The video never plays as smooth as it does when I preview it in Premier.


Here are the export settings I am using in Adobe Media Encoder:

Format: H.264
TV standard: NTSC
Frame Width: 1280
Frame Height: 720
Frame Rate: 30
Field Order: Progressive
Pixel Aspect Ration: Square pixels
Profile: Main (I don't understand what this setting is)
Level: 5.1 (Again, I'm not sure what this setting does)
Bitrate Encodng: VBR 1 pass
Target Bitrate (MBPS): 30
Maximum bitrate (MBPS): 35

Advance Settings (set keyframe distance): I have left this unchecked (not sure what settings to use, if any)

MULTIPLEXER: MP4


For a video project that is 2 minutes 54 seconds long, the above settings result in an MP4 file that is around 350 megabytes in size. But again, it doesn't play as smoothly as the preview within Premier itself, which is disappointing.

My PC specs are as follows:

Quad core 2.6ghz
4 gig RAM
2x800mb hard drive
Nvidia 8800 gfx
Windows XP professional 64bit


I'm pretty new to editing HD video so I could be doing something very wrong. I'd appreciate some advice on the settings I should try using to export the project as an H.264 file please. The more detail (in plain English!) the better.

By the way; I did try to export the video as Microsoft AVI with a view to perhaps re-encoding that in a 3rd party program, however after about 5 hours of waiting for the video to encode, I gave up, suspecting problems. If I export as MS uncompressed avi, the resultant file seems to play only the audio.

Thanks for reading.

G.