Heya,
I have both a 42" Panasonic 1080p Plasma, and a 37" Insignia 1080p LCD. Plasma in general is more expensive because it frankly carries better picture. That's the main difference. It doesn't show up much on television use, at all, because most TV out there just doesn't have the quality needed to actually meet what these televisions can do. But when you use a computer with HDMI output on them, you'll see the difference rather quickly. Since you're using Svideo, that means you're using low resolution (800x600~1024x720 at best), and you'll get no real benefit from either plasma nor lcd in the 1080p large screen ranges. In that case, just get what's cheap and suits you. You don't even need 1080p. Save money and get a simple 720p LCD for like $300~500, if that's what you do mostly. However, if you ever step up to better input, like HDMI, where you can scale resolutions up to 1080p (1920x1080), then get a TV capable of 1080p of course and a nice picture (gonna cost $700~1200 easy).
Plasma generates
better images on a computer. When I plug in my computer to my Plasma, even at maximum resolution of the thing, the text is clear, crisp and colors are right on. When I plug in the same machine to my LCD tv, also a 1080p, the text is not nearly as crisp and colors are not always as good. LCD is a cheaper technology and simply doesn't have the power that a Plasma has. For playing games, the LCD is fine. For reading, the Plasma is far and away better.
Both heat up a lot. Plasma & LCD. They both consume a lot of power; Plasma tends to take more, but that's because of it's higher refresh rates and typically larger screen sizes. People buy big LCD's because they're
cheaper, that's the only reason.
Here's some basic stuff to think about:
Plasma - Typically much higher contrasts, huge refresh rates (480hz!) which is ideal for a computer/bluray, richer color and crisper images when given a high quality signal.
LCD - Pretty much always 60hz refresh, hard to find better (120hz exists, but is pricey, and rare), average contrasts, image from angles isn't the same as a plasma (depends on the screen cover too).
Plasma is just better. It has better everything. And it costs more, due to that. People buy LCD TV's because they're cheaper. There's otherwise, zero reason to ever get an LCD TV.
If you can afford a Plasma, go for it. You want a huge contrast ratio, great refresh, 1080p.
Just understand, again, that the display can't do more than the input quality. Svideo is rotten quality resolution wise (image wise, it's great though). So using a PC on the TV via Svideo will look fine in shows/movies, but it'll look blury and weird no matter what (no matter which TV you use) in Windows, reading text (due to svideo's old tech).
Heres's my 42" 1080p Plasma in action displaying Windows (browing igoogle):
CLICK HERE (plasma). That's at 1920x1080. The text, in person, is crisp. This photo was taken with a digital camera sitting back, and compressed for internet (which is why it's slightly blurred). Next up, is my 37" 1080p LCD in action displaying Windows and playing a DVD in a window at the same time:
CLICK HERE (lcd). It's compressed, but I'll tell you this, I had to put the resolution to 1600x900 instead of 1920x1080 for the text to appear crisp. The LCD works fine for this purpose; I use both. But the Plasma simply displays better image at that 1080p res. The LCD can scale there, but doesn't actually display nicely for PC/Windows/Reading at that top res. I lower it for that one. It is however fantastic for gaming (and hundreds less than a Plasma).
Both work. But the Plasma is superior. But at $500 difference ($1200 compared to $700), I'm totally fine with gaming on my 37" LCD.
Cheers,