Converting video for 16:9 - help



This might be easy for those with experience, but since I'm new to video editing, I find this a bit of a hassle, so please help...

I use a program named Swish for making some simple presentations.

Naturally, I use my PC with standard 15" monitor for making the presentation.

When I finish it, I convert it to mpeg format so I can view it via my home DVD player.

The question is - in what resolution should I make my material to use maximum of the plasma without stretching it.

I googled for explanations about aspect ratios but I don't quite catch that drift.

Also, for converting, I use TMPGEnc. What's the best way to preserve quality when converting from AVI to MPEG, never mind the material size in MB...

So, what should be my project's original PC resolution and what settings in TMPGEnc should I use for best results on 16:9 screen?

If you suggest some other program then TMPGEnc, tell me, and give me some basic instructions how to do it.

Thanks to whoever helps me out!