i notice that new laptops have hdmi output and you can connect the laptop through hdmi to hdmi hdtv. Is the quality in image visible and sound better than connecting through vga/3.5mm cable?? what are the advantages??
Regarding the video, some HDTVs have certain limitations on the PC inputs - say 768P, while most 1080P HDTVs with HDMI will accept 1080P via HDMI. You need to check for each make/model of TV, so one cannot generalize.
Regarding the audio, if you're connecting directly to the TV, due to the quality of the TV speakers, I doubt there'd be a difference.
IF you're connecting "through" an AVR with HDMI audio handling, and if the laptop can send HD audio from say BluRay, then the HDMI connection could be superior. (I don't know if laptops have this sort of capability.)
You sould probably check the operating manual for the recommended input format for the PC input. Since the native resolution is 768P, there may be no benefit to feeding the TV a signal that is higher than that, it may even be "worse" since then the signal may need to be converted twice - once by the sending device and once by the TV.