Have you tried to run your PC in a regular monitor? coz what I think is that your NEW computer is having "NO DISPLAY" problem. Have it checked first, let it boot in a computer monitor then once its running, connect it to your LCD TV again. I have no problems with my HTPC connected to a LCD TV from first bootup - windows install etc...
FYI: LED TV is still LCD TV, the difference is the new TVs that are called LED are using LED as backlight, the old ones are using CCFL. LED = low power, longer life, consistent brightness. So I still call them LCD TV.