Have a look on
www.avforums.com for some more in-depth advice. I'm on my second PJ just now. An Optoma HD65. For 400 quid its a cracking little 720p HD projector. Cant fault it. But be careful as 1 in 10 people are subject to the rainbow effect on DLP projectors, and this can ruin your enjoyment. Best to demo first if you can.
I personally was all set for spending about 2k on a 1080p PJ, until I realised that I dont really use full HD content. I do have a PS3 which will play Blu rays at 1080p, but I rarely buy them, so most of my useage is at 720p for xbox360, ps3 games, and SD for films. So decided to buy this PJ as it got some really good reviews over on the forums, and was only 400 quid. Replacement bulbs are sub 100 quid, and last 3-4000 hours, so should be ok. My first PJ I had for 2 years and put 1000 hours on it.
You dont want to watch TV on a projector anyway, as who really wants to see stacey slaters face at 6ft high splattered over your wall? So mine is used exclusivley for gaming and dvd. Be warned though, light control is a major plus point in this area. You'll want to invest in good quality black-outs. A good screen makes a difference, but I dont use one. And some of the more obsessive out there go as far as painting their rooms almost black (which I intend to do, as its solely a cinema room).
It can become very pricey, but as a starter, I suggest i nice cheap HD PJ just now (like the HD65), just to see if it's for you. It isn't for everyone...