If this is 1080 video I'll bet it's interlaced, and you should follow the Interpret Footage link Mylenium posted above.

You are also woefully short on RAM in AE terms, so you can't use multiprocessing.  Turn it off.  You won't get very long RAM Previews, either.

If you made a high-quality file, your disk drive probably can't keep up with the file's bit rate.  To reassure yourself everything's okay, put that file into Adobe Media Encoder and make an H.264 file, which ought to play back smoothly.

In my experience, if you ask such a battery of questions, three things are usually true: you're new to AE, you think you can learn one or two tricks to get you by, and you think AE can be mastered easily and intuitively.

You are mistaken.  You have to learn the basics of AE.  You have to walk before you can run.  So what do you do?

Fortunately, Adobe's own Todd Kopriva -- the guy who literally wrote the book on using AE -- has thoughtfully compiled a list of resources to help you learn the ins and outs of this marvelous but complex application:

http://blogs.adobe.com/toddkopriva/2010/01/getting-started-with-after- eff.html

I heartily recommend that you spend a good deal of time looking everything over.

Now, to answer some of those questions:

how much ram do i need

I wouldn't run AE 10 with anything less than 12 GB

what kind of disk drive i need i dont think disk drive   the problem?

If you don't have at least two drives, one for the OS and applications and another for user files, you need another drive.  It won't solve your bitrate problem, but it will avert disaster down the road.

is useing encoder  first the only way to to go about this rendering problem ?

It's not a rendering problem -- your drive simply can't keep up with the high bitrate of a high-quality file.  If you want your video quality to go in the toilet, you are certainly free to render in whatever codec you choose.  But for now, double-check your stuff by using Adobe Media Encoder, okay?

i have the raw video and it looks good its hd and everthing when i play the same video in AE  how is it post to look?what i mean is it post to look like the raw video in hd?

I'll assume the phrase "post to look" can be translated into everyday English as "supposed to look".  Yes, it ought to look the same.  But remember that AVCHD is an acquisition codec ONLY.  The video has be bejeezus compressed out of it as the camera records.  It's extremely lossy. It's a one-way trip -- you NEVER want to go back to AVCHD.  If you re-render to AVCHD -- if it can even be done -- it will look just god-awful.

But I think your problem lies in that you shot 1080 video and you didn't interpret the field order properly, so it doesn't look right.  Which brings me back to my original point: learn the basics.