Are you after 26" due to size constraints or because of the budget? 32" generally isn't much more than 26" and looks quite a bit larger than the 6" difference may suggest (37" isn't much more again, though at £400 may be pushing it without going for no-name TVs)
Don't worry about getting 1080p, its pointless until you start getting in to much bigger sizes, like 50"+ (that is, unless you plan on using it as a computer screen also). You would struggle to find many 1080p sets in sizes less than 37", for this very reason.
Where contrast ratio is concerned, if you're using it to compare one screen to another make sure you're not looking at the "dynamic" contrast figure, as this number has turned in to a marketing headline in recent years and doesn't have much bearing on the true performance of the screen. The actual panel contrast would be a much lower figure - a screen with a quoted 5000:1 contrast ratio is likely to have an actual panel contrast of around 1000:1. (and real life measurements in normal lighting conditions are likely to be more like 50:1, but they're certainly not going to publish that figure
)
Have a look at a few in some shops to get the best idea of image quality (though the colours will look over-saturated because they're in their shiny shop sell sell sell mode, make sure you turn this off when you actually take one home). Once you've found a few models you like that are in your price range, scope out all the reviews you can, if they're from the same generation and price range you're likely to find direct comparisons to help you out.
100hz refresh is a nice feature to have just because, but I can't tell any difference and I've even seen reports on some sets that turning it off results in better image quality. I wouldn't go out of my way to make sure that the set has it. 24hz on the other hand actually does make quite a difference if you intend on watching BluRay or HD-DVD. Given that they're all recorded in 24hz, you can sometimes see a slight amount of judder in slow pans in films when playing them at 50/100hz. (I'm exaggerating here, it is actually quite subtle, but its one of those things that once you notice it, it can really start to piss you off)
Longevity is a moot point really, a TV from a quality manufacturer is going to last far longer than you're likely to keep it. Who wants a TV that lasts longer than 5 years anyway, then there's one less excuse to get a new one when the time comes!
And to echo the above, the black levels on LCDs are nowhere near CRT, and you may find the image looks washed out until you get used to it. Tweaking the settings can help this quite a bit, as can professional calibration (though that's going to cost as much as the TV again). You may also notice artifacts when viewing SD content, though at 26/32" they shouldn't be too bad. And you'll probably be viewing quite a bit of SD content, as the quantity of HD broadcasts in the UK is woeful and vastly overpriced *sigh*
, to me anyhow. Also, they all seem to be HD ready, but there seems to be more than one format; 720P and 1080P (better). Is it really important?
.
