Why buy a HDTV when Sky can't even give a date as to when its going to release a HD service? PS3 will probably be the first non-PC HD source.
If you buy a nice Panasonic plasma now, you will get AT LEAST a years use out of it before you need HD. And even when HD is out, you will still be able to scale it down to your screen and it will still look REALLY NICE.
Can get the 42" Panasonic PWD7s for under a grand now and they have VGA in which the XBox360 will plug strait into