SD or HD?

Unless you've converted your whole setup to high definition (HD), standard definition (SD) is probably for you.

MPEG-1, MOV or WMV?

You don't have to decide now — you can download any and all formats of media you purchase. Now, tomorrow, or even next year when you switch software and need a new format. Both SD & HD versions include all three formats.

MPEG-1 consistently shows up as the industry standard but most likely isn't the best format for you. It will, however, work on any presentation software but can be “clunky” on a Mac.

Windows Media (WMV) has emerged as a nice compression for PC users. In most cases, you'll find that it works much better than MPEG on your Windows-run machine.

Quicktime (MOV) is the absolute best option if you're using a Mac. Also, if you're using Pro Presenter or Media Shout on your PC, this might be your best bet as well.