Sure. . . It's possible to use a widescreen LCD, it's just inefficient. You're buying screen area that you'll never use, and you may have to make the cabinet wider to accommodate it. (But you were thinking of making the cabinet wider anyhow, so maybe it's not a problem for you.)
True... but the widescreen LCD's might be cheaper since they seem to becoming more and more common.
For instance, on newegg, there are some 22" widescreen LCDs for a couple hundred less than the ones you pointed out, and a 26" for less, etc.
Another alternative is to just buy a normal TV LCD(rather than a "computer" LCD), you can find many sales of them going on all the time. Many of them have computer VGA/DVI and more inputs on the back, even if they are "just" a TV LCD.
Edit: I just checked bestbuy's flyer this week, they have a 32" 720p (which I belive is 1280x720 resolution) LCD tv for under $500. And I'm sure someone could find much better deals if they started keeping an eye out.
It's been several years since I've bought a LCD. But anyhow, there might still be some 25ms ones turning up on eBay or as refurbs. So I'd say it's still something to not overlook. I've played a lot of games on my Cinema Display, which I think is rated 14ms. I've seen smearing on Bushfire, which has high-speed parallax scrolling (purely cosmetic in the background, didn't effect gameplay), but very few other times has it ever been noticeable.
I agree, its not something to overlook, and could potentially be important. If someone did overlook it, they could be severely dissapointed. Plus the old LCD's had much narrower viewing angles (nowadays you can see them from almost any angle the same as if you were in front of them), and often weren't as bright (some LCD's now are VERY bright. Like easily visible in sunlight bright). So there are additional potential badness factors with older ones.
I'd probably just wait for a good sale for a new one (online or locally) and get one that way. Then I wouldn't have to worry about potential problems with old LCD's
Yeah, but then vector games look sorry on a raster arcade CRT. I prefer the smooth look of my LCD on all kinds of games, authentic or not.
Really? Cool. Makes me feel better at planning to go LCD

I've not yet tried a vector game on MAME, I wonder what the differance would look like between an old vector monitor and a modern CRT or LCD.
Thanks again for that link to that LCD cabinet.