Many people on these forums generally prefer plasma TVs over LCD / LED TVs (without going into detail, an LED TV is essentially an LCD TV). There's plusses and minuses to both technologies, but I wouldn't get bogged down with the technology behind the TV - the best bet is to go with what you think produces the better picture, irrespective of the technology used within it.
The TV originally linked to by BB is a great set for the price - it would be hard to beat that. However, I'd recommend going to check it and some others out in the flesh if you can. I'd also agree that getting a Full HD TV (i.e. 1080p) would be a better long term bet. With an HDTV, a 42" set would be fine at 2 metres, and with high def content, a larger set would be actually be preferable.
Out of interest, is there a reason why you're not interested in HD? As BB has pointed out, any new TV you buy now will be an HDTV - it will upscale standard def content, but the result may well be that you find the picture is not as good as your current CRT - this will be exaggerated if you increase the size of the TV at the same time. Unfortunately this is just a by product of the gradual shift from SD to HD - your old TV was designed to play SD content so is optimised for that, whereas an HDTV is designed for playing HD content, and thus is really optimised for this.
I can understand not wanting to go to the expense of upgrading your Virgin contract, but many TVs nowadays come with a Freeview HD tuner in them which at least gets you the BBC One HD, BBC HD, ITV HD and Channel 4 HD channels - I'm not sure about you, but these channels represent probably 90% of my TV viewing! Blu-ray players are also extremely cheap nowadays, and Blu-ray discs themselves have come down massively in price since last year. A BD player will still play your existing DVD collection, allowing you to gradually increase your offline HD content as and when you want to.
Finally, you can also pick yourself up an internet TV box like the
Apple TV or
Roku 2 XS, or a device which combines both - with its new circa £150 price point for the 12 GB version, the
Playstation 3 is actually a really good deal, given it gives you both a Blu-ray player and access to all the standard UK catch up services (BBC iPlayer, ITV Player and C4OD). It also offers streaming music and movie services, and finally of course, games (but you don't have to go there if you don't want to!). Any device such as this will also give you another fairly cheap route into HD content.
Anyway, I've perhaps gone off-topic a bit, but thought it was worth bringing up the subject for you to consider!