What Spriggan said for sound. You can get them from RadioShack or any other adapter/DIY electronics-based shop. Just get a headphone to to Phon (RCA jacks) and then use regular sound connections... unless you are super on top of it, and need a Digital Coaxial, or Fiber Optic, or direct sound.
As for the HDTV.....
The first question is why do you want to do this? If it is for fun, just to say you did... see #1. If you want to surf and type see #2 If you want a gigantic monitor that makes use of the money you spent for HDTV see #3
#1: If you want the quickest easiest way, it is to grab some cables, use cheap adapters and plug it into the T.V. and tell the computer it has a new/second monitor.
You should be warned, No matter what T.V. you have, the quality of video is GREATLY diminished to the point you will probably not be able to read anything in writing or understand anything except you have a large blurr that is supposed to be an icon or a person on the screen in a movie)Result? Screen looks like crap (you can't read anything, and the icons/images look like the middle of a color pallete from a first grader). This is due to screen resolutions, I can with 90% accuracy say your laptop will send the signal with 480P in 60Hz (really really bad). The picture will be fuzzy, out of proportion (X/Y scale) and it will flash a lot. Not worth the money and time and future headaches you WILL have from looking at the screen.
#2: Buy a cheap converter.
http://www.radioshack.com/product/index.jsp?productId=2104194&cp=&origkw=pc+to+tv+converter&kw=pc+to+tv+converter&parentPage=search$100 is gone like that, but you have a quick, easy connection with a pretty good picture (as a general rule of thumb!! generic HDTV doesn't say enough, there are waaaay to many variables still to say whether or not it will work, like your HDTV resolution and hz., is it 720p/35hz.? 1080p/75hz.? 1080i/85hz.?etc...)
Result: Picture is decent, you can surf the web, write a paper etc... maybe watch a movie, if you like seeing the quality diminished and it looks like a regular T.V.
#3: Finally,... Buy a $100 DVI cable, a $400 HDTV ready/graphics card and throw away your old laptop and tell a sales guy you want the biggest baddest machine (make sure it is a desktop) ever, go home and make sure you are uninterrupted for 6 hours to set up your new system.
By far this will get you the best picture and your T.V. will resemble a monitor. You will get a picture your T.V. was made for, although you will not be able to tune into HDTV signals until the next generation of graphic cards come out.
I am an electronics geek. Feel free to ask any other questions.. ..
....Suppose I got on a little rant......
ummm... Yeah!! I agree with EB, Stupid Universal. Noone would buy those.
