However, some HDTV's have compatibility issues with external line doublers. The most common problem is that the TV locks in widescreen mode when receiving a 480p signal.

Only the older TV sets should do that. I don't know of any new TV sets which have this problem. Newer sets should allow you to do all of its stretch/squish/zoom modes for 480p as well as 480i.

My TV set is a couple years old, so it just so happens that mine has this problem. This is actually an important factor in my choices for buying a progressive-scan DVD player. Because of this limitation of my TV set, I have to make sure my DVD player has built-in automatic scaling. The players based on the Mediamatics chip set have this feature-- the JVC players will automatically scale/stretch/squish the image so it's the right shape for my TV screen.

Something you need to be aware of with the 4x3 vs. 16x9 choice is burn in. CRT's get dimmer as they age. If you are only using a portion of the CRT face then you will get uneven wear and it will become visible.

This isn't generally an issue with tube televisions, as their CRTs don't burn as quickly as those in projection televisions. The projection TVs burn quicker because their CRTs run brighter in order to do the projection. And yes, burn-in is an issue for projection televisions if you leave up a static image all the time. This even counts for those irritating "logo bugs" on many stations. Plenty of owners have complained that the Fox News logo is burned into their sets because they left that station up for a few weeks nonstop.

Part of the problem is that the sets come from the factory with the white-level setting cranked up too high (so they can compete with tube televisions in the store). This is commonly called "torch mode" among projection TV techs. The first thing you should do when you get a projection TV home is to turn down that white level. This is the biggest step to help prevent burn-in. Next is to vary the viewing so that the same static image isn't up 100 percent of the time. For instance, if you tend to go back and forth between widescreen and 4:3 material, you should be fine. And as you said, gray bars instead of black is a big help, too.

My final bit of advice is no matter what you buy, get the AVIA DVD and follow it's instructions to properly calibrate the user settings.

Hear, hear. Avia rocks, plain and simple. I heard the author was working on another version of Avia that was due to come out soon. Can't wait.