Yes, there IS, if you plan on uploading to YouTube or Vimeo, because they will convert your SD rendered to HD in much better quality.
Two of my examples (make sure to hit 'watch in HD) to compare.
http://nl.youtube.com/watch?v=dnUeGQuvcQM
and
http://nl.youtube.com/watch?v=tsWZg2es1gA&feature=channel_page

That's an amazing improvement.

That's a selfish approach IMO. Info here:
http://eugenia.gnomefiles.org/2008/04/11/dont-upresize-your-videos/

If you want HD quality, buy an HD camera. That's the bottomline. Don't game the system.

Hi Eugenia,
I guess I'm being dense again, but I don't understand your point of veiw when you use words like cheating, gaming, selfish, etc. I'm not familar with the process that Ivan used, but it did produce better quality video to watch, and isn't that what we are all after? Whether, Vimeo, YouTube, DVD, PC, TV, theater, etc., we are all looking to produce the finest, highest quality footage we can. You have devoted numerous posts to helping people do just that, why couldn't this be just one more tool in the box of tricks? Take care. Cin

I used to believe that you could not make a silk scarve out of a sows ear but looking at the above SD video rendered to HD on Vimeo stuns my concept. It is obviously better looking (at least on a computer screen). The only downside I see is that it doesn't play quite as smoothly but it definately looks cleaner.

Ivan,

Can you share your process?

Of course I'm willing to describe the process. It is actually pretty basic. I have two camera's: the still image canon A590IS and the canon camcorder MD101, known in the US as the ZR800. The former films at 640x480 (20fps) and the latter is a SD minidv camcorder. Footage from the A590IS is cropped to 16x9, so the resolution is actually even lower, using pan/crop in Vegas.
I filmed my kids feeding the ducks with the A590, the Liechtenstein movie was shot with the MD101.

Here are the basic steps:
1) Under properties, make sure to 'match media settings'
2) Do the editing
3) Under file, click 'render as' and choose WMV
4) Depending on where you live choose the 720p (25fps) Pal template or the 720p (30fps) template. (Actually, I play these on my dvd player also, but if you just plan to upload to Vimeo or YouTube, I don't think it matters)
5) After rendering, simply upload to Vimeo or YouTube.

Vimeo will automatically convert this wmv file to a HD movie (720p) instead of the standard definition. As this is no true HD, as Eugenia pointed out, I never label or tag these files as HD.
Youtube will convert this wmv file to HD as well. Youtube actually makes 4 files. Be patient, because it can take several hours before the high quality version becomes available. When it finally does, simply click 'watch in HD'.